The The Devil Is a Part-Timer!, Vol. 4 (light novel) — Satoshi Wagahara

With his beloved MgRonald closed for renovations, the Devil King's out of work! Worse, the apartment he shares at Villa Rosa Sasazuka has gotten damaged thanks to his fight with Gabriel, which means the household has to temporarily vacate the premises. Having lost both his title and his vast land holdings, the Devil King takes a part-time job at his landlady's niece's beach house--and of course Chiho and Emi insist on coming along. It's summertime at the beach, but the Devil's still got work to do...!