Seven Knights Revolution: Hero Successor

Seven Knights Revolution: Hero Successor is an anime series that aired in 2021.

Based off the mobile game Seven Knights, The series is set in a world where ages ago, warriors chosen by the goddess Serrass banded together as the Seven Knights and stopped forces that were aiming to destroy the world. Now part of legend, these heroes' powers were later inherited by "successors" who also fought to protect the world. One day,a successor of the Seven Knights named Faria saves an ordinary boy named Nemo from monsters when during the ensuing battle, Nemo summons the power of a hero and becomes a successor as well. However, Nemo's hero is a stranger that is unknown to history.

Episode 3
Gildan trains while shirtless but loses control over his magical power and turns into a monster, however he is able to be saved.

Episode 4
Nemo takes a bath, and his shirt flies up while he rescues Faria after they slip and fall off the dorm's rooftop.

Episode 12
Nemo's transformation into his Physis form destroys his clothes, therefore he is completely naked when he reverts back to his human form.