Ya know guys in the end it's a work of fiction. No need to stress about the possibility of him building his own computer at age six. Just take it for what it is. Anyway as expected the pacing seems to have gotten considerably slower since no side stories will be aired this time and it's all straightforward storyline from here on out. I'm looking forward to seeing Yui again. If you've noticed in the OP she was in fairy Kiritos pocket. I'm guessing she became a pixie or something. Cute
Hmmm come to think of it his adoptive mother did say it was from junk parts. If we take that as old computer hardware then might have just put it together basing on watching how his mother worked.