Hitoribocchi no Isekai Kouryaku

Haruka chose to live his school life alone, then suddenly finds himself transported with his classmates to another world where a god lets them choose skills for survival. By the time Haruka's turn arrives, everyone else has taken the useful abilities, leaving him with a collection of strange leftovers, including 'Loner,' which prevents him from joining any party.

Haruka enters the new world the same way he lived before: by himself. Yet the supposedly worthless skills begin interacting in unexpected ways and make him far more capable than anyone predicted. The harder problem is that his classmates keep getting into danger, so the determined loner repeatedly finds himself rescuing people he intended to avoid.