Shooooookkkkk

Ooppss
I read it wrong Σ( ￣□￣||)
Hahah sorreeyyyy

The lion is not Keishi's brother. He is the older brother of the classmate of the calico cat that was an acquaintance of Shingo (Shingo would make fun of him when meeting him at the park). And the Schol Nurse is the lover of the calico cat. Once he saw Shingo attacking the calico cat and kicked him. That was before Shingo meet Keishi.
Keishi has one brother that is Rin's father and that can't properly change into a leopard as Keishi, but he is still a leopard.
The author is mixing characters of three series here.
http://www.mangago.zone/read-manga/kuroneko_kareshi_no_asobikata/
http://www.mangago.zone/read-manga/nekoka_kareshi_no_ayashikata/
http://www.mangago.zone/read-manga/nekoka_danshi_no_shitsukekata/
I holp that helps. : )

Also, if I am not wrong, the lion has three or four half-brothers ( I don't really remember anymore). And his relationship with Keishi is coworkers since Keishi is an actor and the Lion is a model.

three! you are right

No! Just one brother and two housemates

Just follow my List of "Kuroneko Kareshi series" (Even the last 1 has some little connection to their world yet unrelated to werecats, but I still include that 1 on the list)
http://www.mangago.zone/home/mangalist/207252/?filter=&page=1

Relationships:

#Keiichi and Shiou (Lion) are both actors, so they know each other from their line of work

#Shiou is half-brother from Michiru

#Shingo knows Kokonoe (Calico) and Natsume from his past.

#Natsume got another work related to werecats so he got involved with Shiou, Michiru and the 2 housemates (Black Panther & Tiger)

#The Tiger as an author is connected with the editor in "Ikezu Kareshi no Otoshikata" (The 1 that doesn't know anything about werecats. At least never mentioned)

Hope this helps

This is correct order, and relationships d(≧∀≦)b

Perfect ! You said everything <3
I really like that the whole series are connected.
http://www.mangago.zone/read-manga/nekoka_kareshi_no_ayashikata/tr/166552/page/147/
Here the meeting with Shingo ╮(￣▽￣)╭

Thanks (=・ω・=)

Thanks (=・ω・=)