
He broke up with him because he didn't call him? I don't understand that part...
Then who did he call when he got ran over? And who said "Hi how are you?"???

No, he broke up with him because Mirai never takes the first step. Mirai couldn't speak up to him, couldn't explain his reasons. If you can't say to your boyfriend that you called your best friend first because you're childhood friends that live together and he would easily know what to do in that situation then you probably have other reason. Is like... If you can't say to your boyfriend where you're going to he would assume that you're doing something wrong, like cheating on him, or that you don't care about him.
Mirai is kinda of stupid and damn lazy...

BUT IN THE END DOESN'T HE HAVE TO GO AWAY??? THAT CAN'T HAPPEN, BUT HE HAS TO DOESN'T HE?? Σ(っ°Д °;)っ

Nah~ Not really. Iku thinks Seo's a ghost. But actually we still don't know he's already dead or may be just unconscious somewhere but his spirit can't find his body.
As a romance, it's more like the last case which I guess Iku may help him find his body then he recognizes Iku or not will be an issue later..

This expensive one!? (▰˘◡˘▰)
http://www.mangago.zone/read-manga/2345/bt/c002/pg-23/

My previous post is just joking.. I guess it that way because..
- Normally ghosts can't RIP & wander around because they concern about something. But Seo's quite cheerful & concerns nothing though he can't remember anything but his name.
- If he'd been dead, they would have indicated it somewhere. But Iku on found this - http://www.mangago.zone/read-manga/2345/bt/c003/pg-15/
they're step brothers instead of actual brothers, so would this still be considered wrong?
Depends who you ask, but if homosexuality is considered wrong in Japan, then yes?
Well, old bro is of age (above 20) while younger one is underage. So, in that sense, yeah...
Arent both of them underage? I mean, brother left for uni a year ago, so he is now, what 19?