I wanna ask...is this series? if yes, what's the sequence?

yes it is a series and this one is not the first story if you want to i will list it down

oh... pretty please

so this is how it goes:
http://www.mangago.zone/read-manga/kuroneko_kareshi_no_asobikata/
http://www.mangago.zone/read-manga/kuroneko_kareshi_no_amaekata/
http://www.mangago.zone/read-manga/kuroneko_kareshi_no_nakasekata/
http://www.mangago.zone/read-manga/kuroneko_kareshi_no_itoshikata/
http://www.mangago.zone/read-manga/kuroneko_kareshi_no_afurekata/
http://www.mangago.zone/read-manga/kuroneko_to_kareshi_to_ouji/
http://www.mangago.zone/read-manga/kuroneko_kareshi_no_arukikata/
from here on will be stories of other characters:
http://www.mangago.zone/read-manga/fukigen_kareshi_no_nadamekata/
http://www.mangago.zone/read-manga/fukigen_kareshi_no_saraikata/
tho they happend along side tge other stories i dont know the right order here^^*
http://www.mangago.zone/read-manga/wagamama_ouji_wa_neko_wo_karu/
this one is for rio when he becomes older and still ongoing^^
hope it was helpfull:)))

btw i forgot to say
http://www.mangago.zone/read-manga/nekoka_kareshi_no_ayashikata/
this one is where iy all started but its not about shingo and keiichi but iys cute. the last vol of shingo and keiichi is related to this one

thank you so so so much

you r very welcome