Shinozaki kun no Mente Jijou

Shinozaki kun no Mente Jijou summary:

Shinozaki is just an ordinary, everyday office worker burdened by the very normal worry that he might be a bit "off his head."
One day, he's approached by a strange woman named Yuuyake who proceeds to explain that her magician grandmother had long ago enchanted his body… causing him to have a lot of internal machinery?! Apparently, he has to start receiving regular maintenance to stop himself from falling apart…

With that, the slightly wobbly magical remodeling life featuring the very ordinary salaryman Shinozaki and the enigmatic magician Yuuyake abruptly begins.