17 year old Keita Mahiro was simply one who decided to become a shut-in NEET because people disliked him for being extremely prideful and smart.

But it isn't until a little girl that symbolizes death comes by and gives him two options: One, he can die a painless death and no one will remember him at all, or Two, he can get reincarnated as a 15 year old boy named Xander Wiltmar, with the memories of him, and he can transform into a puma.

He therefore chooses the second option, and so begins the adventure of Xander Wiltmar and his harem of girls, as they conquer their ways to fight villians, dark lords, and more. . .