Kanji’s the one to propose it. Not their current arrangement; that came from both Naoto (who’s always been one for fairness and efficiency) and Rise (who vetoed Naoto’s original plan for rotating weekly schedules in favor of something far simpler.)
Kanji’s cool with that part. Who wouldn’t be? What he isn’t cool with is asshole, loudmouth third-years giving Rise shit at school and making her cry. It’s this situation that his proposition relates to, and it basically boils down to three words: "Kick Their Asses". Pretty intuitive, he thinks. Naoto, of course, goes and complicates it - "Discuss Matters First, Then Kick Their Asses" - and Rise wants to alter it further - "Forget About This Crap And Go Make Out."
There is, admittedly, some debate about the merit of the last one. Kanji has to work hard to stay angry, particularly when Rise demonstrates her proposition on Naoto. Naoto probably has to work even harder.
She does a good job, though. Insists loudly that her plan has to be enacted. Defending Rise’s honour and all that. Rise points out honour’s not really a pressing issue when you’ve got your legs wrapped round someone’s waist, but the vote, in this case, goes to the Coalition of Kicking Asses (and Possibly Discussing First)
Rise isn’t impressed. "You’re both crazy. Like I care about rumors!"
But she cares enough to cry, even if neither Kanji nor Naoto ever point this out.
"That’s why she needs two boyfriends," Kanji says, as Naoto and him walk round the back of school and down to the soccer pitch. Naoto’s done her groundwork; two of the assholes bothering Rise are on the senior team. They’ll question them first. Or Naoto will. Kanji’s looking forward to standing menacingly behind her, cracking his knuckles and scowling, that kind of stuff.
Unfortunately they quickly discover two facts:
1. Naoto isn’t very good at questioning people in a non-threatening manner, at least not when they’ve been making Rise cry.
2. Soccer team loyalty is a powerful thing.
"How many players should these guys have?" Kanji asks, throwing the first two into the goalposts. Naoto, kicking the third in the shins, is a little too busy to answer.
Fifteen minutes later, there’s a trail of bruised and whining soccer players from the pitch down to the locker room. Kanji forgot to count them, so he still doesn’t know how many assholes make up one soccer team. But the important part is that two of the morons picking on Rise are down - and they’ll probably go running (or limping) to the rest.
"I think this went very well," Naoto muses while stuffing strips of increasingly bloody tissue up her nose. Trying not to move too suddenly - he swears someone stamped on his back at some point, and he might’ve broken his hand on one guy’s face - Kanji nods and kisses her on the head.
Rise still isn’t impressed. Particularly when Yasogami High gets knocked out the inter-school soccer tournament by default because their entire senior team fails to show. "You guys are idiots," she tells them, while they’re sprawled out on the bed in Naoto’s apartment with ice-packs and consolatory animal crackers. She’s pissed for a week, and takes it out on them in various creative ways. By Thursday, Kanji’s pretty certain that if he maybe couldn’t walk before, he definitely can’t now, and Naoto’s practically begging Rise to stop doing that with her hands, the bruises still hurt, and why can’t she just entertain herself for once?
So yeah, Rise’s pissed. But she isn’t crying. And no-one’s given her shit at school since.
The coalition considers this a victory - and when Rise goes out the room for more ice, Naoto and Kanji give each other a very painful, congratulatory not-so-high-five.