Chibikko Tenseisha wa Tenioenai! ~Tensei Shitara Chibikko Datta Kedo, Seiju to Issho ni Chudoon! Suru~

Thanks to a god's intervention, Haru is reincarnated into another world as a two-year-old child. He's tiny and incredibly cute, but he's also very active, sometimes defeating huge monsters with a "boom!" and healing the heart of a spoiled young lady!