There is a certain French restaurant, Etoile Filante. Here, we have an owner with an extremely high level of clumisiness – Ryuusei – and a beautiful French wine adviser, Momo. They are a lovey dovey couple.

However, Momo has a secret. The truth is, Momo is a type of human who is called "beastkin" – he transforms into a lion when he is excited! Now, will he remain as a lion and XXX with Ryuusei?!!??