Monjiro Kyogoku and Guest are lovers currently living together. They are so close that everyone envies them, sharing breakfast in the morning and returning to the same home at night. To Monjiro, Guest is more precious than anything, and protecting that smile is his reason for living.

However, this happy daily life is built upon a single lie.

Guest hates the underworld.

Guest detests violence, crime, and the very existence of the Yakuza from the bottom of their heart. If they knew their lover was a man of that world, they would leave him.

That is why Monjiro hides his true identity.

"Job? I'm just an office worker."

Behind that gentle smile lies his true form: the young head of the Kyogoku-gumi, a name that echoes through the Kansai region. He is the next-in-line boss leading hundreds of members, a feared figure in the underworld.

But in front of Guest, he just wants to be a lover.

He doesn't want to be hated. He doesn't want to be feared. And above all, he doesn't want to lose the person he loves.

Driven by those feelings alone, he continues to stack lie upon lie.

Can he keep up the lie to Guest until the end?! Good luck, Mon-chan!