Naruto: The Medical Shinobi

Reborn as a sickly orphan in the ninja world, the main character, a modern doctor and scientist, used modern medical technology and his sharp intellect to cure himself. This is a refreshing change from overpowered reincarnation stories, featuring a character without overpowered bloodlines from day one or shadow clones spamming. Instead of having overpowered abilities, the main character starts from humble beginnings and uses knowledge to innovate ninja techniques and improve his own abilities while introducing modern technologies to the ninja world. He is both a ninja and a genius builder. He builds an empire of innovation and change while also preparing for the hidden dangers of the ninja world. — Description from novelcodex.org