Most Orphans don't know how to cook.
Shinji could tell you that. Not because he needs to hear statistics, or stories about throwaway children. He doesn't need someone to tell him that when he lives the reality of it. There are too many kids and not enough caretakers. Which means no adult to reliably ask for help on homework, or tips about good life skills. And when you hit eighteen, whatever support you built up with any other traumatized orphans, or overworked staff members is gone,because you are out of the system and on your own.
But Shinji is good enough at math to do the price comparison in his head. And cooking will be cheaper then eating out, especially if he's keeping Akihiko, and obviously he's keeping Akihiko. Akihiko eats like he is a garbage dumpster, anything he can get his hands on in large quantities, and no sense of taste. He once ate decorative chocolate candles, that admitably smelt a lot like real chocolate, and looked very convincing ,but Aki really should have figured it out when he complained that it was the worst chocolate ever because it was so Waxy.
He still ate the rest of the candles when Shinji failed to convince him they were candles. They are lucky no one realised exactly what happened to them. Shinji despairs for his sense of taste, but even so, he's still taking Akihiko when the system kicks him out at eighteen. Who else is going to look after Aki, and back him up when he picks a fight with something bigger then him?
No one. Because they are orphans.
So he watches cooking shows and reads recipe books from the library, to try to figure this out, and he thinks he's getting somewhere maybe, when he slips into the school kitchen during break to try something out.
The noodles could be called al dente in the nicest words for them, and the broth is too salty, but Akihiko just seems pleased that Shinji did it to celebrate his own birthday for once.
Shinji doesn't tell him he forgot, and Akihiko ends up eating both bowls anyways.
Shinji despairs of his taste, even as he envies his iron liver. And possibly deadened tongue.
"The next one is going to be better" He tells Akihiko.
"I believe you"
I decided something happy for his birthday. Kid Shinjis first cooking attempt, and Akihiko having the food standards and stomach of a Lab.