(Not sure if this is even findable but here goes…)

I’m looking for an older collection of stories that I read in around 2010-2012.

In one of the stories, a boy teaches his friend (a girl who’s in love with him) the western names of stars that make up the summer triangle. Later, after the boy has left (for boarding school, maybe?), the girl uses the western names when talking about stars with her grandma, and the grandma is like "where did you learn those names?" and… scolds her for it, I think?

Basically the girl suffers from unrequited love for the boy who has left for somewhere, and the summer triangle is the recurring motif. The girl and boy never get together.

Details I remember:

• The artstyle was of the "shoujo" variety and seemed dated. I’d guess 90s or early 2000s. The characters had big, round ears.
• The girl and grandma wore kimono as everyday wear, and the boy wore a gakuran.
• It took place in a village / rural area.
• A lot of the story took place outdoors at night, under the stars. I think the girl and boy sat on the porch as they talked.