After Rimuru's encounter with Shizu-san in the manga, he learns how to mimic a human form. However, the body......was that of a three-year-old child!? With chibi-Rimuru and his friends unleashed from the Great Forest of Jura, maternal instincts hit in the Tensei Shitara Slime Datta Ken Official 3rd Spin-Off!

(Source: Kodansha, translated)