Pixelated Heart and Forgotten Memories:

YUGIOH Vrains!

While walking home after school one day, Naoki Shima stumbles over a duel disk abandoned on the side of the road. Wanting one for a while but never having enough money to afford one, he takes it home, unknowingly involving himself in the conflict between two rival organisations fighting over the supposed AI who resides inside it. It calls himself Six and keeps listing three things how he sucks at dueling (along with everything else, on principle).