久々に実家で過ごすことになったが、暇を持て余すリコ（与田祐希）たちの元へ、叔母（和田光沙）と甥の勇斗（長尾翼）がやってくる。久しぶりの再会に盛り上がった一同は、リコと勇斗を家に残してショッピングへと出かけてしまう。取り残され、いてもたってもいられなくなったリコは勇斗を連れ出し夏の自由研究へと出発！
意気込んで虫取りを始めるがなかなかうまくいかず、悩んだリコは矢島模型店の暖簾をくぐる。そして、勇斗と一緒にプラモデルを作るべく、リコはある作戦にでる…！
Riko (Yuki Yoda) and her friends are spending time at her parents' house for the first time in a while, but they have too much time on their hands when their aunt (Misa Wada) and nephew Yuto (Tsubasa Nagao) come to visit. The group is excited to see each other again after such a long time, but they leave Riko and Yuto at home and go shopping. Left behind, Riko can't sit still, so she takes Yuto out and sets off on her summer research project! She starts catching bugs with enthusiasm, but has no luck, and worried, she goes through the curtains of Yajima Model Shop. Then, in order to build a plastic model with Yuto, Riko comes up with a plan...!
