Before returning home, Sawaki and his friends meet Marie once more and learn that the messages left by the microbes helped her family to resolve their differences and move on with their family business. Finally back at Japan, Hasegawa wonders about what she should do from then on, as with her engagement cancelled, there is no reason for her to remain at the university, but Sawaki encourages her to move on with her carreer not for obligation but for doing what she really wants to.
龍太に自分の本当の思いを打ち明けた長谷川は、また大学に戻ることを約束し、沢木たちと笑顔で別れる。
一方マリーも、沢木と菌たちのサポートで父親と対峙する。ようやく互いの気持ちを知る二人。翌朝マリーは、黄金丘陵で父にある提案をする。
