Two kids go to a training camp for their moms' volleyball club. At the camp, they get into some naughty behavior by playing pranks on each other's moms. The four of them take a bath together and wash their mom's back, but their mischievous Kokoro start to bubble up... They're so curious about her oversized breasts that they don't just poke them, they massage and lick them too. They can't sleep if they all sleep together, so they're playing a little prank on their friend's mom, who suddenly wakes up, and they start playing a little prank on her. The moms get serious about their kids.