from Blissful Sin:

"I wonder… if I’ve become lecherous."

High school student Hiroki yearns for his best friend Yuuji's father, Seiji. He has tried many approaches, but has only managed brief exchanges. Yuuji told the depressed Hiroki “I’ve fallen in love with you…Why don’t you forget about my father!” However, Hiroki bravely began the process of captivating Seiji. Before long, the aimless lover is being loved, Hiroki’s body being ravished…
In the shocking three part series, Idol Unit “Boku-chan’s*” series. Drawn for this special release, a tank-full of even more love, debauchery, and worthwhile reading collected in this omnibus!!

From Fantasyshrine:

1) Boss' Favorite
Sakurai is a new hire who is having a secret relationship with his boss, Chief Akimoto. Even though the chief is gentle, suave, and unexpectedly, a pro when it comes to the H-department, he’s still an “old man” in Sakurai’s eyes! However, Akimoto sees right through the rather naive Sakurai and spoils him to the point that keeps him demanding for more… until they both come to regret it!

2) Secrets Under the Suit

3) Until There's Love

4) Cat Lover

5) Butterfly and Flower Lovers

6) Secretary's Choice

7) The Favorite Subordinate

“You’re like a child, Sensei!” is what Ono said as he stared at his favorite teacher… who is also a man…

The teacher-in-training, Shiina, never intends to have a relationship with the perfect student, Ono. Instead, he watches him from a far and tries to continue to learn how to be a good teacher. But one day, Ono reveals he has feelings for Shinna too! What's a teacher to do with a love sick puppy like Ono?

from Blissful Sin:

“I want to satisfy my heart and body…!”

What does it mean to become a pair of lovers? Confessing love, having sex, does that alone make you lovers? When did the feeling of falling in love become a greedy luxury?

A special publication, “Rising Feelings” and more, in this large compilation full of hard romantic love stories!
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This volume also features two couples that first appeared in her other work Anbalance Lover.

Arisaka x Shirafuji from ch8 here and ch1 in AL.
Eiji x Yuusuke from ch2 here and ch7 in AL.

Chapter 5's Yano x Inoue are a sequel to Chapter 1 in Body Check

Shirafuji's feelings of physical intimacy between him and a classmate, Arisaka, are piling up. He wants to know how Arisaka truly feels about him, but he doesn't have the courage to ask, without exposing his "true feelings." He is terrified of getting hurt, even a little, but now it seems that his love is about to lose sight of reality.

Two couples from this volume have sequels in another of her works Agetai Kimochi.

Arisaka x Shirafuji from ch1 here and ch8 in Agetai Kimochi.
Eiji x Yuusuke from ch7 here and ch2 in Agetai Kimochi.

Chapter 5 is hard shota content, and not scanlated for that reason.