Sword Art Online: Andāwārudo no Kenshi

In which Kirito gets an odd Fatal Bullet MC as a partner, the games are canon, it's basically explaining said MC's origins in the first few chapters, Sachi, Yuna and Yuuki gave the middle finger towards death, the plot includes Attack on Titan as an excuse for Kirito having badassary in his blood, and Kirito meets Loli Quinella instead of the duo in his first STL Dive.

Or, even more simply, FB MC's horrible attempts at wingmaning Kirito and others for no reason at all but ends up with a girlfriend instead, much to his confusion.

Or, even-even more simply, my take on SAO for the reason of having fun.