A-Rank Party wo Ridatsu Shita Ore wa, Moto Oshiegotachi to Meikyuu Shinbu wo Mezasu.

I Left My A-Rank Party to Help My Former Students Reach the Dungeon Depths!

Yuke, a red mage, angrily declares that he's leaving Thunder Pike, the A-rank party he's been with for five years, because he's fed up with being insulted and ridiculed by the other members. While searching for a new party, he runs into his former students Marina, Silk, and Rain, and decides to join their party, Clover. Encouraged by their admiration of him as their teacher, Yuke leads them in completing several quests that show off his own extraordinary magic and skills while bringing out the girls' abilities to their fullest. Then, through an "adventure broadcast" by an artifact known as Camelot, Clover becomes well-known throughout society. The party's dream is to conquer Achromatic Darkness, the most challenging dungeon of all, but as they take on other dungeons in hopes of eventually achieving that goal, they gradually become entangled in chaos that threatens the whole world... (Source: Crunchyroll)