Cooking
There is a reason why Reiji is the only one to cook.
Kazama is the type of person to consider instant ramen a meal filled with nutrients. Reiji thinks that is why he remains so petite. Of course, it's not like Kazama has time to eat. While his squad is eating lunch, he is filing his squad's papers and taking care of errands for the commander, while they take a break, he is taking care of Tachikawa's files (he has never done them, and otherwise Kazama gets assigned to doing them on weekends). Reiji has noticed that Kazama never gets full meals.
So, as a solution, Reiji has decided to make Kazama a bento each morning, which he leaves tucked in front of his squad room with a note only reading:
For Kazama.
The first morning he receives it, Reiji watches as Kazama eyes it, then leaves the bento outside, convinced that it was some joke or mistake.
When the bentos keep coming day after day, he starts to pick them up, and upon finding that the food is not poisonous, after all, and actually quite delicious, Reiji is internally delighted to see Kazama absent mindedly eating his bentos as he files papers. This is not quite the dream result Reiji wanted, but he is now sure that Kazama at least gets one good meal a day. Reiji ends up figuring out Kazama's favorite food (katsu-don curry) based on the leftovers when Kazama leaves the empty bento next to his door on the way out.
One day, a month after he started leaving the bentos, he places the bento down, and then leans on the door of the squad room waiting for Kazama's arrival.
Kazama strides in at the ungodly hour of 4:30 am, dark circles under his eyes, and Reiji wonders whether he should start including sleep medicine.
They lock gazes, Kazama looks surprised for the briefest of seconds, and then gives a tiny smile of thanks.
Reiji feels warm the rest of the day, thinking of that rare smile.