School Trip, an Abrupt Attack
Issei and his classmates arrive in Kyoto. Although Issei is ready to enjoy Kyoto to the fullest, getting stronger is s always on his mind. However, it seems training isn't the only thing to worry about in Kyoto. Powerful groups have begun to move.
Aired 24/04/2018EP 3 - School Trip, an Abrupt Attack
2018
High School DxD HERO
Issei and the 2nd years attend a class trip to Kyoto for well-deserved relaxation, leaving the senior and junior class students of the Gremory family behind. However, once there, they fall under attack and must win without Rias or their other powerhouses.
(Source: Anime News Network)
Note: Includes episode 0, Taiikukan-ura no Holy.