Onnamaou-sama wa Yuusha-kun o Taosenai. - Vol. 1 Ch. 10

[gearsky]

Even though Maou denies it every time, the perceptive futon had feeling it's onee x shota.

Man, that manga had real effect on this site's comment sections, huh.
I've been seeing that joke show up everywhere recently. I laugh every time.