2boys arm_hair bara bed blush bulge bulge_to_ass chabashira_tatsukichi covered_abs covered_nipples erection erection_under_clothes greyscale large_pectorals leg_grab lying male_focus mature_male monochrome multiple_boys muscular muscular_male on_back original out_of_frame pectorals shirt short_hair shorts sideburns spread_legs sweat thick_eyebrows thick_thighs thighs yaoi