It is Spring. A young woman, left by her husband, starts a new life in a Tokyo apartment. Territory of Light follows her over the course of a year, as she struggles to bring up her two-year-old daughter alone. Her new home is filled with light, streaming through the windows, so bright you have to squint, but she finds herself plummeting deeper into darkness; becoming unstable, untethered. As the months come and go, and the seasons turn, she must confront what she has lost and what she will become.