"shinseki no ko to otomari dakara" appears to be a Japanese-language title or phrase; translated roughly it can mean "Because (it's) staying overnight with my relative's child" or "Staying over with my relative's kid," depending on nuance. The appended "1 new" suggests either a first episode/chapter or a newly released entry (e.g., "1" as volume/episode and "new" indicating recent release or update).
Without a specific source (manga, light novel, anime, web novel, doujinshi, or fan work), the phrase most likely refers to a slice-of-life or domestic short story premise centered on a stay/overnight visit involving a relative's child ("shinseki" — relative/kinsfolk; "ko" — child; "otomari" — overnight stay). Such premises often explore themes of family dynamics, caregiving, childhood perspective, boundaries, and everyday humor or warmth.
The Protagonist (Yoshida): Yoshida is a relatable lead. He isn't a dense harem protagonist nor an overly cool alpha male. He is earnest, easily flustered, and genuinely considerate. His internal monologue drives the comedy—he is hyper-aware of the awkwardness of living with a girl his age and is constantly trying to maintain "proper distance." shinseki no ko to otomari dakara 1 new
The Heroine (Saki): Saki is the highlight of the series. In typical Uoyama fashion, the heroine is expressive and slightly eccentric. She isn't a cookie-cutter "tsundere" or "kuudere." She has a bubbly, sometimes chaotic energy that contrasts with Yoshida’s straight-man routine. She is comfortable in her skin but clearly harbors a specific reason for wanting to stay over (which drives the underlying plot beyond just slice-of-life fluff).
The story begins with a classic setup: Yoshida is a high school student living a quiet, somewhat lonely life. His routine is disrupted when his aunt asks if his cousin, Saki, can stay with him for a while. "shinseki no ko to otomari dakara" appears to
The twist? He hasn't seen Saki since they were very young children. He barely remembers her. When she arrives, she is not the little girl he might have expected, but a high school student his own age.
The core hook of Volume 1 is the immediate friction and awkwardness of this arrangement. They are relatives, but practically strangers. They must navigate sharing a living space, dealing with morning routines, and the social intricacies of high school, all while trying to define what their relationship actually is. The Female Lead (Relative):
The Female Lead (Relative):