Honorifics: Epel

Epel typically refers to his fellow first-years with the “-kun” honorific.

Exception: Epel drops the honorific from Deuce and Ace’s names in Book 5 after a conversation about how he is under order from Vil to use “-kun” with everyone.

Epel refers to all second-year students with the “-san” honorific with no exceptions.

Epel refers to all third-year students with the “-san” honorific.

He uses the “senpai” honorific once with Vil during Phantom Bride, and it is also how he refers to Vil in his Book 7 dream.

Bonus: Unlike other characters who use hiragana for honorifics, Epel uses katakana (the alphabet for foreign loan words) with his fellow students, but not with people from his village.

Epel is under order from Vil to speak more politely, which might be the only reason he’s using honorifics at the school at all. Hence his use of katakana: it’s possible that using honorifics in an environment like NRC is foreign to him–he is not used to it–but he is used to the people from his village, which is possibly being symbolized through hiragana.