A Summer of Beginnings

Same school as Flower Grown in Purity. Same group chat. Same gossipy cheerleaders.

On the last page, it's clear that Okugawa intends to send
a dick-pic of Sanada to her friends, which is a funny way
of showing us that (contrary to what Sanada might think)
she's still as mischievous as she was as a child.

The sexual proposition sequence on pages 10-11
is a masterpiece, sweet, sensitive, and brilliantly
understated.

Okugawa tugs on Sanada's shirt.
(page 10, panel 3)
Okugawa says she'll be lonely without Sanada.
(page 10, panel 4)
Okugawa clasps Sanada by the hand.
(page 10, panel 5)
Okugawa casually selects a pack of condoms
from the shelf.
(page 11, panel 3)
While holding the condoms, Okugawa asks for
permission to visit Sanada, in order to "study."
(page 11, panel 5)

The whole thing is perfectly paced, as Okugawa
realizes how much she loves Sanada, and calmly
decides she's ready to give up her virginity.

Sanada gets the message loud & clear, so it's no
surprise when we see them getting busy on the
very next page.

That's three of four that have a work featuring them in this friend group. The last one remaining is Yoppi. Hopefully soon, these have all been masterful.

As thedecline18 notes, Momoko's last three chapters take place
in a shared universe. The FMCs in those stories are all members
of the Usajo Cheer Squad. Ponytail-girl in this chapter is Nagisa
from A Flower Grown in Purity. She's also the "Nagi" whom Aki
calls for sex advice on the last page of My Sister's Cute Friend.

If I know anything about teenagers, Okugawa's friends
will be thrilled & delighted when they see the dick-pic.