Well, Midori is a terrible person, but they've dropped a couple hints in recent chapters that he might have some Dark and Troubled Past to explain his being a sadistic Manipulative Bastard. Perhaps more importantly, Hotaru's said that she sees "making enemies into comrades" as one of the goals of survival games and has shown a somewhat inexplicable willingness to make nice with Midori. All this seems to indicate that at some point, maybe after Toy Gun Gun manages to win the TGC championship, bygones will be bygones and it'll result in a Defeat Means Friendship moment that, in all probability, will turn Midori into a Karma Houdini.
WMG / Aoharu × Machinegun
They're paving the way for some kind of Hoshishiro HeelFace Turn.Fujimoto is already a Nice Guy and has formed friendly connections with both Hotaru and Tohru, talking openly with Hotaru after the TGC match and offering to help Tohru improve his strength and stamina (and following up on it). Ichi has slowly been shown as less of a Cute But Psycho Dark Action Girl, giving Hotaru advice on how to better her aim and receiving more sympathetic portrayals depicting her feelings for Midori and her vulnerability regarding him. Midori...
Haruka became an overachiever for Haruki's sake.Haruka idolizes his brother and saw that the pressure put on Haruki was making him unhappy, so Haruka decided that he would succeed for their parents to take the burden off of Haruki. That just made Haruki look even more worthless in their parents' eyes, creating further resentment in Haruki against his brother, which wasn't helped by Haruka's intense feelings about Haruki and his lack of restraint about showing them. Haruki pulled away and Haruka kept increasing his efforts, trying to recapture the closeness they had as children, but only succeeding in scaring Haruki off entirely.