Kira has adopted many habits since becoming a Lieutenant. Waking up at dawn, for instance, so that he can get an early start to his day. That is, he wakes up at dawn when he goes to sleep at all. But that isn't the point.
He's always written haiku, as it gives him a way to let off some of his many pent up emotions. Then, after Hisagi became a Lieutenant and an editor for the Bulletin, he started letting Kira publish those haiku in each edition. Eventually, Kira became an honorary editor as well. But that isn't the point either.
The point, really, is that Kira spends a little bit of his day every day at the Bulletin with Hisagi. He's noticed many things about Hisagi. Some of them are good things, such as how hard he works. Others… Are questionable. At best.
For instance, there is Hisagi's habit of eating things that had gone bad. Very, very bad. To counteract this, Kira has made a habit of making two bentos every day. Four if he has the time. Two so that he and Hisagi can have lunch together. Two, when he has the time, so that they can have dinner together as well. All to minimize the chances of Hisagi killing himself via food poisoning.
All of this, of course, is leading up to the fact that when Kira enters the Ninth to have lunch with Hisagi, as usual, he is instantly when he sees Hisagi hunched over something at his desk accompanied by the familiar sounds of him eating something. Something that, knowing him, he probably really shouldn't. Like, really shouldn't.
"What are you eating?" Kira asks immediately. His suspicions are confirmed when Hisagi only hunches more over the mystery whatever and starts eating faster. Kira comes closer to take a better look. What he sees horrifies him.
Rice growing mold. A bit of what looks like used to be fish, but a very unhealthy shade of green and - is that a maggot? Ew.
"Spit it out! Spit it out right now!" Kira cries out, moving to grab the very, very gone bad food from his no-longer best friend. Hisagi tries to keep it from him. With some effort, Kira manages to get the dish itself away from him. Now to get Hisagi to spit out that last bite.
They scuffle some more before Kira manages to force Hisagi to spit it into the trash can. Before Hisagi can start cussing him out, he shoves Hisagi's bento into his arms. Then, after a moment's thought, he pushes his own over to Hisagi as well. He isn't hungry after that sight. Content now that he has food yet again, Hisagi starts to demolish the two lunches.
With Hisagi distracted by a much more appropriate source of nutrition, Kira takes the time granted to empty out all of the fridges in the Ninth and Seireitei Bulletin of any more questionable substances. He also reminds himself mentally to start doing this at least once a week, if not more often. Because really, what else is he supposed to do?
"I really need a raise," he mumbles to himself. Because really, he does.