@mogima note the hair came from the comb, so it means it's not fallen hair, it's hair pulled from the scalp and thusly more likely to retain follicles.
Wanted to mention that Koibumi (Love Letter) is actually the first story of an anthology compilation.
(Via bakaupdates : https://www.mangaupdates.com/series.html?id=146725 )
The first chapter is the oneshot listed already here,
https://mangadex.org/title/36597/love-letter
the second story...