@Goldenzeal
Its "Arifureta Shokugyou de Sekai Saikyou". After being kicked down like a total loser so many times, regardless of how one girl's feelings are, he still obtains her affection, but as well the scorn of various boys.
The entire classroom gets transported to another world where magic is a thing. Next, after a dungeon raid went wrong, he gets caught in a 'stray shot' of a spell. Arm's bitten off, and he encounters a "God Crystal", a rock that drips a Heal-All liquid to be consumed. In a desperate hunger, he ate monster meat raw. It changed his physique violently and drastically that he became stronger than before by a factor of 5. Doing what any survivor does, he fought, he killed, and he didn't trust anything till he encountered a sealed room.
Opening the lock, he saw a little girl, chained up and barely alive. The MC didn't want any trouble and began to close the door before she desperately said "I've been betrayed!". Cursing himself, he decides to free her, only to awaken a guardian of the room. Killing it, the MC realizes that the loli is a vampire with an insane regen with a huge drawback, her regen is based on her mana-pool.
The story goes on with only one goal in our MC's mind: Head home. Then he modifies it to: Head Home with my loli.