A female friend who missed the last train ended up staying at a guy's place. As they slept side by side, the guy got excited seeing her large breasts. He secretly touched them, and noticing she was aroused too, he pulled her into the futon to have close contact without her making noise. Another girl watching from outside the futon also got turned on and crawled in, leading to a harem-like scenario where he was sandwiched between two large-breasted girls.
