Shiro gets a pet what is it and what are they named?
I think Shiro can reasonably be expected to take care of a fish.
They don't need too much attention, just food daily and their tank cleaned every once in awhile. It's also not going to make a mess of his home.
The fish was not his idea. Rather it was imposed on him by Mariko who was in the process of moving and needed someone to watch her fish while she sorted it out.
Shiro was against it at first, but Mariko pulled rank on him, he reluctantly accepts it.
The fish is named Sakura. I'm not entirely sure what type of fish it would be because I don't know much about pet fish breeds.
Shiro gets stuck with Sakura for longer than expected. Mariko keeps getting wrapped up in other stuff and she needs him to watch her for "a little while longer".
Shiro is annoyed but still takes care of Sakura. She gets fed once a day and he makes sure her tank is well cleaned. However one day he notices Sakura isn't eating and it continues to the next day.
Shiro of course starts panicking because he thinks he killed Mariko's pet fish and he's faced down several super villains, but he won't be able to handle a heart broken Mariko.
So he rushes then fish to vet and despite demanding to be seen immediately is stuck waiting for a few hours. Eventually he's seen and Sakura is checked out.
The vet says she's fine just a minor bacterial infection. He's given fish antibiotics and told to get a separate tank for her until the infection's gone.
Shiro starts watching Sakura like a hawk. Making sure she's well cared for, replacing her tank with something larger, whenever he goes out he comes back with a decoration for her aquarium. He also starts letting her eat out of his hand instead of sprinkling food into the tank.
A few weeks go by, Mariko's finally finished moving in and arrives to take her fish back.
Shiro won't admit it but he's sad to see Sakura go. Once Mariko's settled into her new place, Shiro is visiting a lot more than he used to. However he's more or less hanging around Sakura's tank and inquiring Mariko as to how she's doing rather than anything requiring his cousin's well being.
Eventually Mariko decides that both Shiro and Sakura would be happier together if the fish moved back in with him.
She can't be obvious about it though, or Shiro would refuse. So Mariko gets a cat and tells Shiro that her newest pet is causing stress to poor Sakura and it would be so wonderful if someone could take her off her hands.
Shiro agrees and happily takes Sakura home with him.
He's never going to admit it, but he loves that fish.