Takahiro Miki and Tomoe Kano’s 2021 film The Door into Summer (夏への扉 キミのいる未来へ) is an adaptation of Robert A. Heinlein’s 1957 novel The Door into Summer. Directed by Miki and written by Kano, it stars Kento Yamazaki, Kaya Kiyohara, Hidekazu Mashima, Natsuna, Naohito Fujiki, and a cat whose name I failed to determine.
Soichiro Takahura (Kento Yamazaki) has experienced tragedy after tragedy. He was orphaned, then taken in by his father’s benevolent colleague Koichi Matsushita. Alas, Koichi and his wife died in a mishap soon after. Koichi’s daughter Riko (Kaya Kiyohara), briefly raised as Soichiro’s sister, was taken in by her uncle Kazuhito (Hidekazu Mashima) and although they are still close, Riko no longer shares a household with Soichiro.
By 1995 Soichiro has three things on which he can depend: his R&D work for the robotics company he co-owns with Kazuhito, the companionship of his cat Pete, and the love of his stunningly beautiful girlfriend Rin Shiraishi (Natsuna).
Probably it’s not significant that Pete hisses whenever he sees Rin.