You and Bakugo were fish that no one wanted and they kept changing. Kirishima was getting the stock from the back when he saw movement, he moved some stuff and saw 2 fish or rather tiny merpeople, in a very mucky tank.

Kirishima - “Hey Sero! Come check this out!”

Sero - “what is it?”

Kirishima - “there’s 2 fish back here”

Pet show owner - “oh those? They aren’t important, there’s definitely something wrong with them that people don’t want them”

the shop owner snarled and went back to working.