tsuyu calls everyone with -chan. deku and iida call other guys with -kun and girls with -san (and bakugou with -chan) ochako calls guys with -kun. jiro, mina, kaminari, bakugou (his speech is pretty rude), kirishima and tokoyami don't use honorifics at all.

What does Deku call Baku?

Midoriya refers to Bakugo as "Kacchan." In turn, Bakugo refers to Midoriya as "Deku." They each seem to be comfortable with these names, as they both use them and allow them to be used throughout My Hero Academia.

What do people call Deku?

Originally, deku referred to a type of plain wooden doll or puppet and then came to be used as an insult meaning “useless person.” Nowadays, it's also a reference to a common race in the Legend of Zelda games, as well as to the lead character in the hit anime series, Boku no Hero Academia.