Manga by author Oumi Noko - Status ongoing

Seko Daiko, a second year high-schooler is an extreme cheapskate. Taking down all the light bulbs in the house, making his siblings eat baked bread crush for breakfast... He would do anything just to save an extra penny.Daiko was sure he could keep this thrift lifestyle going forever until... The world's fate depends on him spending money on a mobile game?!

""Become a hero!" With that dream in her heart, Shirumiruku Eru became an adventurer. But becuase she had no special skills, she struggled to find companions. That's when she got the chance to join the dungeon investigation led by Yuris, a great sage who specializes in healing. However, rumor has it that all adventurers who accompanied Yuris have had their spirits broken and abandoned their path as adventurers halfway through You see, Yuris had a bizarre interest in getting excited by the sight of female adventurers being attacked by monsters. And so begins a cruel adventure where death is never an option!