Demon King Hero: I'm Not the Protagonist?

The confused Mu Yu came to the goddess's space and was forced to become the goddess's experimental mouse? At the critical moment, Mu Yu's golden finger showed his power, winning the goddess's first kiss and unlocking the achievement of a macho man! But he was sent to the finale with a palm from the goddess. But I never thought that in the second world of the reincarnated Demon King, when I thought I was embarking on the path of the protagonist where small monsters give experience, big monsters give equipment, and BOSS pushes me to the pinnacle of life, I was shocked to find that I was only a supporting role? ! But it doesn't matter, under the dual control of his own professional ethics and Golden Finger, Mu Yu successfully counterattacked and became the protagonist. There are just a lot of flaws in the process. My sister is too enthusiastic. The Demon King is a stupid and cute loli who mistakenly thought he was a hero and relied on him! The shy school girl looks at me in a weird way! This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.