The Dirty Way to Destroy the Goddess's Heroes, Vol. 2 (light novel): No Reply. It's Just a Saint.

After defeating the heroes, Shinichi is ready to live out his happily ever after-—until a powerful light spell blasts through the sky, marking the arrival of his newest enemy’ the Saint! Shinichi is all too eager to take down this adversary, but when he realizes she’s surrounded by holy warriors around the clock and won’t fall for his sweet nothings, he scrambles to come up with another plan. The latest rendition of his genius scheme somehow involves the daughter of the Demon King and a dir...