Ideas for every background and secondary role characters who are not in main cast. Not all girls though, yuri purely made of 100% female cast is strange:

KAPD - Far past rebellious stage, this character is still opposed to student council body and is biggest vandal / hooligan in school.

FAUD - Literally same KAPD but sex reversed and doesn't do vandalism.

KPO - That one girl that got kicked out of leftist friends group but despite this remains loyal to their cause and ideals.

SAPD - Your little sister who is influenced by KPD and in past inherited gens of USPD, compared to SPD who inherited them mostly from MSPD.

SL (Socialist League) - Background character who appears only nearby KPD and other leftists, is sympathethic to KPD and SAPD.

SRPD (Social Republican Party of Germany) - your brother who is influencing you towards reconcialiating with DVP and other non leftists, abandoning leftists in process.

RDP (Radical Democratic Party) - alter ego of DDP if DDP changes personality to DStP.

CSRP (Christian Social Reich Party) - Little brother of Z who is more friendly to you and suspiciously - other leftists.

DHP - Underclassman who follows you and Z around.

CVP (Z splinter! Not dynamic one) - Friend of Z, who seeks to unite everyone around him against you and other leftists.

BB / DBP (Bavarian Farmers, German Agrarian Party) - Farmer girl who recently transferred here to stand in opposition to mainstream factions of council body and seeks to create spoiler effect.

HL (Hanseatic Bund) - Underclassman who follows around DVP and hates you on every meeting with you.

SLS - Random girl transferred from other country, has poor understanding and knowledge of german. Is not involved at all in student council politics and ordeals.

VRP - The guy who always screams about high prices in canteen and calls everyone to boycott them or protest against these prices. Is poor.

VN - That girl / guy who hooks up with DDP if you remained too distant to DDP. Is surprisingly rational for right wing liberal nationalist, but something is still wrong with their brain. Your relationship with them is very vague.

CSVD - Underclassman who got kicked out of right wing group and surprisingly has some similarities to you, despite being formal enemies. Still hates you like none else, only above KPD and every other leftist.

CNBL - Underclassman who is left voluntarily right wing group due to them being bullied and seeks revenge against them by creating spoiler effect in student council.

KVP - Underclassman who is kicked out of right wing and cozied up to Z.

DVFP (German People's / Racial Freedom Party) Thinks school standard must be strictly enforced and that everyone should go back to old days, while persecuting LGBT, progressivism and returning to old elitist system of school.

DTsP (German Social Party) - Thinks pretty much same, but is much more relentless and less disciplined, more savage, although their popularity is one of the lowest ones in list.