After winning a basketball tournament, Koichi Mizuki is magically summoned by Prince Caius Lao Bistail to Tildant, a world ruled by titans. Caius declares that Koichi is his bride and begins the 'bonding'.

A flashback reveals how a prophecy decreed that Caius could never wed someone from his own world, which prompted his decision to summon Koichi in the first place.

Koichi agrees to stay with Caius for a period of one month; in exchange, Caius agrees to not do anything to Koichi against his will, and to return Koichi to his home world after the month has concluded.

Koichi and Caius attend a party where the country sees his summoned bride for the first time. However, an ex-fiancee shows up unexpectedly. Will she be friend or foe?

Koichi and Caius enter the land of the Beastmen in search of a fruit.

Caius and Koichi meet up with two Beastmen who say they can get them the Raisa fruit.

Caius leaves Koichi alone at the inn to make the trade for the Raisa fruit. Meanwhile, an intruder finds Koichi and kidnaps him.

Caius rushes to save Koichi from his kidnapper. He orders the kidnapper to get him the Raisa fruit and gives him an ultimatum.

On the brink of death, Koichi and Caius share a tender moment while waiting for the Raisa fruit. Will Baro get back in time to save Koichi?