Bitter Sweet Luck

Asagi Saikou is a short, but mature eleven year old girl, a late bloomer. She tries to be the bigger person but it's hard to take her seriously because of her small stature. Though, she doesn't complain nor does she care.
Recently, her best friend, Nima Ueno, a tomboyish, but shy girl her age, started acting more feminine and started to socialize more. Thus, their friendship was drifting apart, but not quite non-existent.
Asagi found out the reason why: HER FRIEND WAS A LEAD IN A HAREM BETWEEN POPULAR BOYS IN SCHOOL!!!
One is a quiet, standoffish soccer player, another was a mischievous, possessive skirt flipper and the last was the most popular boy in school due to his mature looks and personality.
Asagi came to the conclusion that if Nima were to have a boyfriend, she would spend more time with him than her.

What will Asagi do being apparently a side character of the shoujo harem?

*Inspired by 12-sai, a shoujo manga by Nao Maita.