8-nin no Senshi

The tournament to choose the next king of the islands is about to begin. The rules are simple—whoever comes first loses! To ensure they don’t, participating warriors protect their mighty swords with armor that grows larger and more elaborate with each tournament. But one warrior who’s been studying abroad has returned with a secret technique certain to force a pleasurable eruption! Is there a warrior alive able to withstand it? Or is this deft warrior destined to become king?!
(Source: SuBLime Manga)
Note: Originally serialized under the title "Pulau Senki" (プラウ戦記), officially renaming it to "8-nin no Senshi" in early 2019.