Isekai is really popular in this community. haha Though I haven't watched a lot, let me give this one a try...


Anime Title: 生きろ (Ikiro or Live)

Plot: A couple of childhood friends, Kei and Aki aim to tick some entries on their bucket list. They're both adrenaline junkies, so a number of them involved extreme activities like wingsuit flying, cliff diving and so on. On one of their planned adventures, cave diving, Kei unfortunately couldn't make it due to unforeseen circumstances. Although disappointed, Aki decided to go through with the plan alone, but he never returned. Kei desperately traced his friend's whereabouts and found himself underwater in a mystical sand cave. Once he entered deeper, something strange happened. And the last thing he saw were fragments of the cave collapsing. When he regained consciousness, he was welcomed by a very familiar face in an unfamiliar world.

Then the theme song of this anime would be Ikiro by NEWS.