Shichisei no Subaru

Synopsis

Haruto Amō leads his six-member guild consisting of elementary school friends called Subaru on a quest in the MMORPG game Union. When encountering the dungeon boss, Asahi Kuga is killed in the game protecting Haruto. Asahi subsequently dies from heart failure in the real world, resulting in the game being shut down. Six years later, the game is relaunched, now called Re'Union, with only invited players allowed to play the game. Haruto is one of the invited players, and after clearing a dungeon he is surprised to find Asahi sleeping inside a treasure chest.

(Source: Wikipedia)