Okay, I have have “answer” of sorts to this topic, but it requires a lot of other bits of knowledge, and it’s awkward to explain, so this is gonna be a long one. Tl;Dr is that the dreams are a revelation and foreshadowing into the mechanics of the world, granted to Riki assumably by Yuiko.
I’ll also start with a reminder that a big part of Yuiko’s character is her seeming lack of existence. She is part of the broadcast club, and she plays Piano and sends messages through it, but nobody can hear her. It isn’t until Riki suddenly notices it that Yuiko is heard.
First, we should establish the common symbolism of the route. For example, rain appears to be representative of the feelings Yuiko holds. That isn’t to say the connection is positive however; rain is often used to frame the strange happenings of the world. From the point where the two became romantically involved, the rain fell, and it serves as a device to isolate Riki (or maybe even Yuiko) from everyone else.
Quotey
{Kurugaya}“I think my tragedy is that I’ve never had this feeling before.”
{Kurugaya}“Before I met you guys, I didn’t even realize how unfortunate I was.”
{Kurugaya}“I didn’t know what was fun and what was boring.”
{Kurugaya}“I didn’t know a thing.”
{Kurugaya}"…Not even what it is to be in love, or to like someone."
{Kurugaya}“But…”
{Kurugaya}“Now… A little.”
{Kurugaya}“Maybe just a little.”
{Kurugaya}“I think I understand.”
{Kurugaya}“I was happy to hear your words.”
{Kurugaya}“That must mean that…”
{Kurugaya}"…we feel the same way about each other."
{Riki}"…"
Neither of us said a word.
…And then I felt a drop of water on my nose.
The rain was starting to fall down.
{Kurugaya}“These are my true feelings.”
She spoke in her usual tone.
Rain shows up multiple times, such as when Riki realizes no one else can hear Yuiko’s broadcasts:
The day ended without any major events.
It rained for the rest of the day, so our practice was cancelled.
{Riki}“Sigh…”
I threw my body on the bed with a sigh.
I’ve never liked rain much in the first place.
With how it shows up, it could be said that the rain is a representation of Yuiko’s isolation. It constantly seperates her from anyone else, in more ways than physical. It almost erases her, washing her away from the world.
There are also several other motifs that couple with this. “River” shows up in one of the dream sequences, and it has a parallel with rain during the Kud route.
KUD ROUTE SPOILERS
The girl who was trying to be a gear that nobody wished for.
Her body so tiny and fragile,
it looked like nothing more than a thin crystal needle about to break at any moment.
The water level was getting higher.
Rain?
Or river water?
{Kud}“It’s time to say good-bye, Riki…”
Her voice was gradually growing distant.
It was the voice of one who had given up everything.
Just before Riki fights against the world at the end of the Kud route, in the scene where he uses his teleportation magic, Kud has given up. She is ready for the world to reset, and in that moment an image of rain and a river appears.
The river motif appears again in the Mio route. She says “If it could manage to ride on this river wind, it might be able to go any distance.”
To go further, this scene appears not long after:
{Nishizono}"…Do you remember the conversation we had at the riverside?"
{Riki}“Which conversation exactly?”
We had brought up too many topics to be sure.
{Nishizono}“About the Hyakunin Isshu containing a number of love-related poems.”
{Riki}“Yeah, I remember it.”
{Nishizono}“Sutokuin, for example, wrote one relating his feelings to the river current.”
{Nishizono}“Even if people see the same scenery, some will think it’s just a river…”
{Nishizono}“While others may be reminescent of their beloved ones separated from them.”
{Nishizono}“The way we define the world varies depending on one’s feelings, memories, and experiences.”
{Riki}“Yeah, I think so, too.”
This is the inspiration for Mio’s poem. In the context of Yuiko’s route, I take it to mean “if you can keep the flow of water going, you can continue to ride it” or something of that sort.
As Mio says, the definition of ‘river’ in the context of Mio’s route is much different than it is in Yuiko’s route. There is a notable inspiration however, as we learn that the origin of this river imagery stems from a love poem about memory and perception.
As for the actual dreams…
dream 1
She had been holding my hand ever since then.
{Kurugaya}“Oh, my bad.”
She let go.
And that instant…
{Riki}“Ah…”
My knees buckled.
…The warmth of Kurugaya-san’s hand enveloped mine again, feeling hot to my touch.
{Kurugaya}“What’s with you, you tell me to let go and then grab my hand again…”
{Kurugaya}"…Young man?"
{Riki}“N… o…”
I’m okay.
I tried to tell her that.
…But my head hurt too much.
It was a pulsating pain, as if my head was in a vise.
{Kurugaya}“Hey… What’s wrong!?”
I’m okay, I’m fine.
I tried to move my lips.
…But my body was no longer listening to me.
My vision went gray.
…Then everything was dark.
And I…
{Kurugaya}"…Riki-kun, get a grip!"
I leaned over on Kurugaya-san.
{Riki}(Ahahaha… I’m just so pathetic…)
That was my last, fading thought before I was plunged into darkness.
{Riki}(Do I… have to sleep again, no matter what…)
…My headache didn’t end.
Even while I was dreaming, the vise on my head kept tightening.
…It was darkness.
Yes, darkness.
Everything was covered in darkness.
{Riki}(No…)
It wasn’t even darkness. Darkness only exists where there is\r
light.
So, this was…
Yes, it was nothingness.
…I wasn’t seeing anything because there was nothing to see.
And that felt like salvation to me.
…Only my headache never ceased.
But here, that was the only proof of my existence.
This dream serves as a mechanical explanation. This is an inner-world Riki is forced into, that is supposed to be completely empty. Riki says that the lack of anything is a good feeling, and that his headache is the only thing he has in those moments. In some way it could be considered a representation of himself, and maybe that’s how they used to be, however as we go further into the route, something happens…
dream 2
…Amidst the darkness.
Amidst the darkness, there was nothing.
{Riki}(Ah, again there’s nothing.)
{Riki}(Maybe I won’t have to dream anymore…)
I could only feel time moving faster.
I wondered how long would have passed since I fell asleep, when I wake up.
I felt as though I heard the sound of a piano.
It felt as though it was a melody I had heard before.
…And I thought I heard the sound of rain.
…White.
I was looking down at the city from somewhere high above.
Looking through the misty haze.
The air is so white, I thought to myself.
What was I looking at? Something far away, something obscured by the white mist.
A line…? A contour…?
A thin beam of light was piercing the whiteness.
On the other side of the whiteness was a lake. Its surface was still as a mirror, not the tiniest ripple disturbing its tranquility.
When I looked up, I saw white cotton falling.
It was snow.
When the flakes reached the surface, they disappeared as though seeping in.
And nothing remained.
Ah…
I put my hand on the glass.
The glass before my eyes was white because of my breath.
It must be cold, I thought as I gazed through the glass.
…And even a dream such as this would be forgotten once I woke up.
This dream starts off by echoing the sentiments of the first dream. The darkness and the nothingness return as a staple, however the dream changes… Into one with a piano and rain. His city appears from outside the glass, but it is surrounded by fog of war. A single beam of light reveals a mirror of a lake, which consumes the snow that falls from above. Riki is overseeing all this from isolation behind glass.
Side note: It is strange to use the anime as material here, but the OP of refrain includes a similar birds eye view. It pictures the school as a white fog erases it. However before it completely erases, it cuts to a scene of Riki running through a warping environment and into darkness. He then wakes up in a classroom.
It’s implied that this is a narcoleptic dream, but something is different about it.
dream 3
I turned my gaze to the window.
It was still raining.
…Is it ever going to stop?
{Riki}“Hm…”
I’ll be able to go out with Kurugaya-san anytime, when it finally lets up…
I let out a big sigh.
{Riki}(Maybe I should give her a call…)
I took out my cell phone and dialed her number.
{Voice}[The number you have dialed is not in service at the moment, or is turned off…]
{Riki}“Weird…”
Did her battery die or something?
That’s something I can’t do anything about.
I let out another sigh.
I don’t know if things are going fine between us or not…
Sometimes we’re at odds over the weirdest things…
{Riki}"…"
I started becoming aware of the fact that I was alone.
{Riki}(I hope tomorrow comes soon…)
I took a glance at the calendar.
{Riki}“Eh…”
…What day was it today?
{Riki}“Hm…”
Whatever…
I looked out the window one more time.
{Riki}(Hope it’s a clear day tomorrow.)
With that thought I fell asleep, earlier than usual.
…My eyes were still shut.
{Riki}(…Hm…)
I heard something.
The sound of a piano…
{Riki}(What song is that…)
Half-asleep, I wondered to myself.
I think I’ve heard this tune before.
And also…
{Riki}(The same thing…)
{Riki}(…happened before…)
It was evening.
The wind was strong.
I was probably by the riverside.
The grass was rustling in the wind.
…Or that’s how it felt to me.
In truth, no sound reached my ears.
There were fireflies flickering by the river.
That’s the image I got, of them quietly dancing around in the darkness.
If I ran through the grass…
…they’d all fly up at once, what a sight that’d be.
But…
I only watched the spectacle from behind the closed window.
…Will I forget this dream as well, I wondered.
It was still raining.
{Riki}"…"
Why won’t it stop…
This dream is distinctly different from Riki’s narcolepsy. He falls into it very easily, and there are things within it. The piano returns, but Riki is in a strange state. He isn’t fully asleep, and he is now overseeing himself within the environment from before. It’s at this point that the idea becomes obvious, that this is Yuiko. Riki, hearing the piano, looking out of the window, all alone, is now in the shoes of Yuiko. He watches the fireflies dance and play, and wishes to run up to them, but instead he remains looking from behind the window. The most important line in my opinion here is “I was probably by the riverside.” Riki saying this, even though he is completely detached from the scene, is the telling moment of whose perspective this is.
Something to point out about these two dreams is the weather. In the Yuiko-perspective dream it is raining, whereas in the fog of war dream it is snowing. The rain dream seems more grounded within an environment, and the snow dream’s world feels hazy and less defined.
Snow is further referenced as Riki figures out the world he’s in isn’t correct. At this point the rain stops and the snow begins.
more dreaming
{Riki}“Ugh…”
…My consciousness…
My consciousness was fading away.
It had never happened at night, before…
…I tried to fight it back.
Through my blurred vision…
I saw…
0:00, 6/21.
{Riki}(Aah…)
Maybe this finally puts an end to this ‘strange’ world.
When I wake up…
Everything will be back to normal…
I won’t have…
to suffer like that anymore…
I hope it’ll really be like that…
I heard someone talking.
‘Everyone’ was talking.
…Why is ‘everyone’ else talking?
Let me talk with you, too.
But my voice didn’t reach them.
I looked up at the sky.
There were stars.
It was dark, it felt like there was only nothingness.
And amidst all this I heard ‘everyone’s’ voices.
…But it’s okay, I’ll be fine…
…‘everyone’ is there.
…Even if it’s a dream, I’ll never awaken from it.
My voice didn’t reach them.
I just kept looking at them from behind the clouded window, listening to their dialogue.
…I’ll never wake up.
…But then, why am I here…?
{Riki}"…"
…
…I looked outside the window.
It was still snowing.
This dream continues the detachment. Riki is back in the nothingness environment, however there is a sky with stars. It’s clear that Riki is still in the same environment from previous dreams, however for some reason the scenery no longer exists. He is still sat behind the glass, but the scene outside of the glass has changed. Riki hears voices, and he can’t communicate with them, but strangely he is okay with this. He’s fine because “everyone” exists.
He says that even if this is a dream, he won’t wake up from it, which implies this scenario is truth. Even if he were to physically awaken from this dream, there wouldn’t be any real difference.
At this point, I believe Yuiko’s problems are transferring to Riki. Early into the Yuiko route we see Riki get involved with (and try to solve) Yuiko’s issues, and a similar thing is happening here. He is now looking out of the window in real life. He is now the one split from the Busters. He is now the one that nobody can hear.
It’s also worth mentioning that, despite the bouts of narcolepsy, Riki constantly mentions how he hasn’t gotten to sleep. There are multiple things you can take from this, but personally I think that either the Narcolepsy is compensating for Riki’s restless nights (making these weird dreams occur more often than in other routes) or that the Riki we play as isn’t the one doing the dreaming. This would line it up well with the post-refrain Yuiko ending that hints the existence of dream-world lives that continue to remain there even after the Busters leave.
Going back to defining imagery, let’s look at ‘white’, ‘snow’, and the sound of the piano.
almost the ending scene
{Riki}“Why…”
{Riki}“Why isn’t anyone listening…”
{Riki}“I know you can hear…”
{Riki}“You can hear her voice…!”
{Riki}“Why isn’t anyone listening!”
I screamed.
But no one turned to me.
It seemed like not even my own voice reached anyone’s ears any longer.
…This isn’t fair.
The gears could no longer be shifted back.
The sound of a piano remained in my ears.
…The artificial sound of an electric piano…
{Riki}(…The piano…)
The melody that no one could hear.
I was always listening to it.
When it was raining, and when Kurugaya-san began losing her memories.
…And when it was snowing too.
I was always listening to it.
I finally found the only rift in this world.
{Riki}(If…)
{Riki}(If I can still get through to her…)
I took out my cell phone, and dialed Kurugaya-san’s number.
{Voice}[The number you have dialed is not in service at the moment, or is turned off…]
It didn’t connect.
{Riki}"…!!"
I dialed one more time.
Just one time is enough.
…But it was useless.
{Riki}“I can’t…”
{Riki}“I can’t get through to her anymore…”
It must’ve been an omen.
I should go to the broadcast room.
I left the classroom.
…It was still snowing outside…
The entire world was white.
{Riki}"…"
Until a moment ago there had been a classroom behind the door.
But now it was entirely covered by white.
Behind the door was a perfectly white space.
I could hear the classroom noise from far away.
…The classroom was just before my eyes, but it seemed so far.
Meaning that…
This dream is coming to its end, and everything is awakening.
Everything is disappearing from the ‘stage’, now unnecessary.
I…
I realized that once swallowed by the white, everything would be gone.
This white space didn’t ‘exist’.
It was empty.
It was blank, there was nothing inside.
This is after all of the dreams, and now we can collate all this information.
The world is now a mess, and Riki is all alone. All of the previous elements come together to create this scene. Riki can’t be heard, but he can still hear the piano. The piano is super important here, as it frames the timescale of the story well. For as long as it was raining (from the moment Riki and Yuiko got together) and continuing as it snowed, Riki was listening to the Piano. We know it was there during the dreams, but it was also there outside of the dreams. Yuiko was playing her melody all throughout the confusing destruction of the world, and Riki could hear it.
The dream from way back, when it was snowing and foggy, now comes into play. This is what the world looks like when it is about to end. If the rain is the signal of the world ending (as we learned from the Kud route and can infer from refrain) then snow is the signal of the world continuing beyond that natural end by force (or maybe just a sign of the world’s struggle to continue being.) The rain kept on going, the world’s reset was forcibly rejected, and the piano kept playing.
The thing you really have to question is how Riki dreams within a dream world. We do see other characters dream, such as Kyousuke does early into the VN, however in all cases it can be said that the dreams are truths. They are other bits of content from the dream world. Riki’s Narcolepsy lacks any content because of this, because he doesn’t have memories of any other routes, however the strange Yuiko-related dreams do have content.
The piano playing, the constant rain, the strange dreams, and the transformation of Riki, are all things put in place to tell us that the world is being messed with by the piano player. The early dream is foreshadowing that if the world continues in such a way, it WILL fall apart, and since the world continues in such a way, it does fall apart.
There’s a lot of other stuff you’ve probably inferred from bits of this post. Unfortunately I didn’t think about organizing this post before I wrote it, so I’m kinda just generalizing the whole thing into one conclusion for the sake of completion, but there’s a lot of random branches you can follow. There are a lot of motifs (stars, lakes, etc…) that I had no space to mention. I didn’t even clarify that the extension of the rain begins with the day of the date, which implies an initial understandable forced-continuation by Yuiko to not miss the planned date with Riki, which further implies a continuing extension as she falls deeper in love… Or, for another example, that the “haze” from the wintery dream was born from the rain, as explained in one random sentence part-way through the route.
There’s a LOT in this route guys.