Well, not really. There are going to be some walls of spoilers next, so if you didn’t read Rewrite’s VN completely before, you better not read it, I guess… Indeed, game didn’t give a full story of Midou and gang, but you can find bits and bites in Terra and Chihaya’s route. First of all, in Chihaya’s route Midou states, that he lost that, that Kotarou still have. He couldn’t walk on the same road, that Kotarou now walks and that he got his power too late. Then we have a solid piece of Terra contributed to Kotarou’s experience in a Middle East (or some minor Asian country). He mets Jasmine and kids there, then he learns in a rather cruel way that all of them are mamono users. Most of them die in process of this revelation by hand of either Guardian, or a completely devastated Louis. Later, when Kotarou manages to save Jasmine and a couple of other kids, there is a remark, that Jasmine picked up kids who called themselves MIdou, Tenma, and Tenjin. Based on all of this and CG’s in the end of Terra (there are Jasmine together with Midou and gang), we can guess, that in Chihaya’s route Midou was refering to the fact, that he couldn’t protect Jasmine and got his power (Fogo) way too late. Well, indeed, this is close to speculations, but given anime’s piece of info now, this all looks rather plausible. Midou loved/liked Jasmine, he couldn’t protect her, then he went to Japan’s Gaia, there he got Fogo, but as it was too late, he had nothing but resentment to those, who simply lives in peace and knows nothing about civil war’s hardships. There in Japan he comes across Kotarou, who is all that he hates. Kotarou is a power user (hunter), he has no real sense of danger, got a girl he wants to protect and she is still alive… Literally, Midou is another possibility for Kotarou. Actually, Kotarou from Akane’s route is a bit similar to Midou (IMHO), though he still got his sole salvation there.
I hope this wasn’t completely “off-topic”.