tried the suggestion forum before, but here i go again:

Can someone suggest me some dramas that center around FRIENDSHIP, like the formation of a Friendgroup, preferably in high school but not necessary?

Nobuta wo Produce. Exactly what you asked for, HS friend group formation. I loved it. Actually, I loved it so much that I also want suggestions of similar dramas, but I don't have any to add.

Brush Up Life is the best I've seen for female friendships. It's complicated and I found it hard to get into, but once it hit its stride it just got better and better.

Summer Strike

(has a bit of romance but mostly friendship)

Shujin-ko 2019

Kashimashi meshi 2023

Ichiban Sukina Hana (slight romance)

Kimi no Hana ni Naru 2022

Its summer film 2021

Muchuu-sa Kimi ni 2021

Maiko-san Chi no Makanai-san 2023

Reply 1988 is a must see.

 smallville101:

Reply 1988 is a must see.

Isn't that korean?

 GentleRain:

Ace wo Nerae! 
Akira to Akira 
Attack No.1 
Cat Street 
Ganbatte Ikimasshoi 
Ghost Friends 
IS - Otoko Demo Onna Demo Nai Sei 
Kisarazu Cat's Eye 
Last Friends 
Life 
Lipstick 
My Boss, My Hero 
Nobuta wo Produce 
Pretty Guardian Sailor Moon 
Stand Up!! 

Great list!!
"My Boss, My Hero" is my comfort drama, I love Gakky's smile in this <3
"Pretty Guardian Sailor Moon" was a part of my childhood memories, Keiko was so stunning, ofc, she's always.
"Last Friends" had such a good plot, and was unexpected.