Maou wa Yuusha no Kawaii Yome

The final battle with the Demon King. The hero, Shion, is betrayed by his four beautiful companions and blown up. However, he is saved by the Demon King, Villa, and survives . He begins living in the Demon King's kingdom with Villa, who saved his life. Meanwhile, the crime of the four who betrayed Shion begins to come to light...?!

(Source: Nico Nico Seiga, translated)