I Am Behemoth of the S-Rank Monster, But I Am Mistaken as a Cat and I Live as a Pet of Elf Girl

The elf girl Aria is an adventurer. She has a lovely face that attracts almost everyone. Her breasts are ripened to the point of almost exploding. And then being embraced between those breasts was a little animal…his name was Tama. He looked like a cat at a glance but Aria and her surrounding companions failed to notice a fact. Tama was a human who had reincarnated and his true form was not that of an ordinary cat. Instead, he was a monster of the strongest class, an extremely young Behemoth. (Source: Novel Updates)