Debo Tangosekku is a Debo Monster themed after Children's Day and armed with the Kenka Ryōseiba, created to serve Dogold by emitting the white Koi Fog from his Koinobori End-Space to kidnap young boys to his hidden village to make them violent to the point of being beserk.
In his koinobori form, he can emit the red Terrible Koi Fog that confine himself and an opponent permanently into a different dimensional space. Though defeated by the Kyoryugers, Debo Tangosekku is enlarged before being destroyed by Raiden Kyoryuzin.
In It's Here! Armed On Midsummer Festival!! Special DVD, he revives alongside Debo Tanabanta as the ghost Festival Brothers and possesses Nobuharu Udo before being destroyed by Kyoryu Red and Kyoryu Gold.
100 Years After
- Height: 212 cm (53.0 m: giant)
- Weight: 172 kg kg (430.0 t: giant)
- Debo Tangosekku's name is derived from the "Boy's Festival".