Need help its been bugging me

#1
The story is like SAO the AI takes over and traps everyone in the game. The MC is named Hine or Cline and is an orphan who the AI dubs the most adorable creature and he gets adopted by the stongest swordsman and his elf wife. If I recall correctly he gets trapped in a dungeon and becomes a half dragon/phoenix. Can anyone help with this its like a song stuck in my head and I can't remember the name.

Thank you.