Mixed Bathing in Another Dimension: Volume 2 by Nagaharu Hibihana

Touya Houjou, a hero summoned from another world, joins two girls, Clena and Roni, in their quest to find the desert kingdom. The fabled kingdom, said to be the home of the demon lord, is shrouded in mystery and intrigue... But what happens when they meet a self-proclaimed sage who claims to know all the secrets? And in what ways will Touya continue to pursue his mixed bathing adventures when his Unlimited Bath levels up?!