1boy, 1girl, bedroom, black eyes, black hair, blush, breasts, closed eyes, completely nude, curtains, dudunia, from side, girl on top, half-closed eyes, hetero, hug, indoors, kamijou touma, kiss, kongou mitsuko, large breasts, long hair, nipples, nude, sex, short hair, sitting, spiked hair, straddling, sweat, toaru kagaku no railgun, toaru majutsu no index, upright straddle