ichika matsumoto, the niece, stays at the house of her free-spirited uncle yamada. ichika only plays games all day and does not listen to anyone. ichika exposes her beautiful ass without any protection. yamada cannot resist and buries his face in ichika's ass. at first, ichika is surprised by the sudden act, but she soon enjoys it and starts to tease yamada, asking for more. from that day on, their secret relationship begins.