Hamomoru Tachibana is an overly serious, easily-flustered clergywoman on vacation in early-20th-century Kyoto who stumbles into a remote forest road near a shrine festival and meets Chuuya Shingoh — a curious student of sciences studying a phenomenon he calls the Star-seeing Basin, where pebbles seem to grow into stars that may influence the city in ways resembling onmyou divination. A lost wallet keeps Hamomoru in Kyoto longer than planned. A gentle arrangement is reached: lodging in exchange for helping with research. Together they walk the streets of Kyoto each night, tending the Basin and watching what blooms.