Maou ga Zutto Miteiru Ellie is My Idol

Synopsis

One day, Reynolds, a demonic youth who worries that the job of "demon king" is not suitable for him, finds a purpose in life. That is to support Ellie, a brave girl who is single-mindedly working towards her dream of "defeating the Demon King." This is a story about a demon king who can't take his eyes off the hero! (Source: Shogakukan, translated)