An Encounter with the Unknown is the first episode of My Roommate is a Cat. It was aired on January 9, 2019 in Japan.
- Kazuhiro Mikazuki (portrait)
- Saho Mikazuki (portrait)
- Subaru Mikazuki
- Sonoko Tanabe
- Hiroto Yasaka
- Atsushi Kawase
- Haru Mikazuki
- Hachi (flashback)
- Haru's siblings (flashback)
- Tora (flashback)
- The funeral and the Door to the New World scenes are exclusive to the anime.
- Sonoko, Hiroto, and Tarō are introduced much earlier.
- The two female strangers from the manga are replaced by Sonoko and Tarō who noticed Subaru checking below the house.
- Subaru feeds Haru a can of tuna instead of mackerel as in the manga.