Kemono Series by Fujisaki Kou

This is the first story in the series revolving Toudou's family.
This story is about Toudou Akira an university professor, who is a single parent and an university student, Tsuzaki Yuuhi.
Features the introduction of Akira's younger brother, Kazuki and Saijou Chiharu, Kazuki's tutor.

This is the second story in the series.
This story take us deeper into the relationship between Chiharu and Kazuki.
When Kazuki finally realize his feeling for Chiharu but he needs to go abroad.
Also introduces Kirishima Kaoru as the representative of the Fujido Groups, Chiharu's co-worker.

Third in series, this is the continuation to the previous volume featuring Chiharu's assistant, Kirishima Kaoru and Daigo Mikihisa, Mercury's managing director.
Kaoru met Daigo at the night club and having one night stand.
Kaoru is a free man who didn't want to get too close to his partner, but Daigo is different from the others.
This story telling us Daigo's effort to breaks Kaoru's wall.
Also follows up on the relationship between Chiharu and Kazuki.

Fourth in series, this continues the story between Kazuki and Chiharu.
Kazuki, the heir of Todou Group, decide to work in the company as a student part-timer with an alias.
Chiharu who feel anxious about their relationship, can't control himself when he sees Kazuki getting friendly to Daigou.

Fifth in the series, this is the continuation of the story between Kaoru and Daigou.
They are business colleagues by day and lovers by night.
Due to his deep-rooted insecurities, Kaoru continuously tests Daigou's affection.
And now, Kaoru's previous boss and lover Ian Evans wants Kaoru back.
While trying to keep his composure, Daigou need to make Kaoru realize that he can't live without him.
Also included: a side story about Chiharu and Kazuki

As Kazuki and Chiharu starting to get 'lovey-dovey' in their relationship, a suspicious document came saying that Chiharu had the plan to take over the Toudou group.
Because of that document, Chiharu's unknown past was exposed.
Kazuki who didn't like people who take advantage of him, don't know what to believe and getting more confused when Chiharu admit that he indeed taking advantage of him.

This is a story between Kaoru's ex-lover, Ian and his secretary, Sanada Manabu
Ian is a play boy with a new pretty boy in his bed every night and Manabu, whose secretly in love with Ian, manages nearly every aspect of his life, including his sex partner.
Reaching his limit, Manabu decide to seduce Ian and become his sex partner.
Also include : a side story about Chiharu and Kazuki who spend every weekend together, but come work-time on Monday with different mood.

This is a short story between Kazuki and Chiharu.
Kazuki wakes to the realization that he fell asleep while having sex with his lover Chiharu. While Chiharu trying to hold back, Kazuki still hungry for more and decide to seduce Chiharu.