Okay

Spoiler
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I read the novel and if this goes the exact way the novel went then the Lizzi is going to tell her to back off because she is wrong if she thinks that everyone is her property because they are game characters and thats not true they have feelings and they are real and not just some game trophies then the girl will try to break Lizzi by saying Bern is the bonus character and will one way or another be hers and then Bern (he has some relly good hearing or can read lips) comes and is really pissed off and tell that girl to get lost and that he isnt hers he will never be hers and that Lizzi is the only one for him and even if that wasnt the case hed never look at her seeing how she plays around with ever guy then that girl leaves and Lizzi cries (i think) and hugs Bern and hes really pissed 

Okay so first that teacher Rö (thats how im gonna call him here) and Berns family blood ties 
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Okay first things first Berns mother was the daughter to the previous kings which is why he was in danger at the begining for being in line to the throne but what does that have to do with the teach Rö? Everything because the woman who had sex with the king and got pregnant was of that house (family or vassal) but that woman died and ger daughter was raised by the house Rö the Duke saw her as his daughter and loved her then the Duke Bern (katrin and berns dad) fell for her and mader her his mistress . I think she died (or is sick) and duke Rö offered help to Bern because he knew that his dad wasnt treating him right. He also knew the duke wwas using him for crimes (yall remembered how bern straighf up killed a dude? Happens more often in the novel) and trained him too bern became his double agent (which is why it was so easy to blackmail the duke into giving Bern the titel)
So and the teacher the woman he loved was Berns mother they grew up together 
He is also the guidance teacher for the shadow student council and is after duke Berntein the onlt other duke is Rö and he uses the info from the shadow council to punish nobels 
The teacher Rö and the duke Rö are both on Berns side which is why the teach said that Lizzi is so important for him /them because she makes Bern happy

Next shadow student council (SSC) and the next big plot point attemped murder
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The shadow student council is the real student council its the real power at school one of the school rules may be "to forget your status here and make conections" that dosent mean to act as you want the SSC watches all the students checks their background as well as their familie (if ther are crimes or so they WILL find proof send it to duke Rö and he will charge them in court) so if they see someone acting out of line they will inform duke Rö who will thwn contact the families or the next higher instance to discuss wherever or not those people should still get their titels 
So now lets jump a little 
Right now Lizzi has a confrontation with that Girl she claims all the boy Bern tells her to eff of and she leaves Lizzi gets sad stuff happens and one night Lizzis dormmate dosent come back she stays in another room and a dude who is a super fan of that Girl climbs in through the window and tries to Kill Lizzi she is saved by her dormmate coming back (? I think) the dormmate admits do having been blackmailed by a one of the capute targets into not going back to the room but she did because she sees Lizzi as a friend and couldn't forguve herself if anyting happens. The dude us arrested by the SSC members and Bern who immediately rushed there Lizzi is still shocked and is suppos to sleep with in the dorm mothers room but she follows Bern , who is interrogating that Dude he tells her to leave and she says my all time favourite sentence in the whole novel 
"We are going to make a family together, husband and wife , as your future wife its my right to interrogate people with you together we will share the burden!"
Anyway she is bad at it Bern takes the led they break his fingers and he tells them everything Lizzi dosent get much whats beeing said and so do we as a readet because shes a UNRELIABLE NARRATOR 
Anyway Bern gets everything he want to fullfill his plan

Berns big plan and the princes and the puppeteers downfall
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So let's first talk about that Girl (i call her that because i forgot her name sorry not sorry) what does she want and where does she come from? Well first of all the rumour about her being duke Rös daughter is false its a rumour the teacher spread because the puppeteer behind that girl went to the duke Rö witb some kind of deal for his help in making that Girl queen the duke agreed because hes been trying to get that familiy for years for crimes (no nobel house really know whos backing the SSC and bring all of the people to court) so that puppeteer holds that Girl brother( her only family) as hostage when she was young she started to remember her past live and told her brother about that that puppeteer somehow found out about that and thought that it was more like a future prediction thing and decided to use her as a pawn make her queen like she predicted would happen and the use her as queen he manipulates her and controls her and if something dosent go the way the game would have gone he hurts her brother (?)
Bern works with the duke Rö and together with everything he had collected on information in and out school they confront the prince, Girl and the puppeteer 

when Bern confronts the Girl with everything and tells her her brother is freed and save now (i think they brought him in like in a tv show) breaks down sobbing and crying telling them that she is sorry that she dosent love the prince or any other guy at school and that she only wants to life in peace with her brother 

The prince is shocked by that and cant believe it because he was so sure she loved him for him and he only wanted to make something for himself that wasnt an order from his father and thats why he wanted to marry her for love and now he has no queen candidate and then Bern says "you dont need one because you are not gonna become king" the prince???? Bern just tells him that only because here at the school you dont have to act with status restrictions dosent mean you can neglect your studies and responsibility and that due to his behaviour the king decided to declare the second prince the crown prince . The prince freaks out and says that unfair etc. The prince thought that he could do what ever he wanted at school which isnt a thing. He broke his engagement without consulting the palace and lost reputation because of his behaviour 
(The same goes for the other capture targets i think)
Then they confront the puppeteer and he kind of confesses and believes that the teacher Rö and duke Rö would back him up but no they dont he gets arrested on the spot 
But it then handes a knife by teacher Rö to stab Bern and the puppeteer does it this was part of the plan because Bern never wanted to become duke he wants to marry Lizzi and life in her small fief /home state they planed to have "Bern" die there at that knife and get the puppeteer also for murder(because a small stab like thaf wouldnt kill professional trained assasin Bern) BUT Lizzi didnt know that and jumps in gets stabbed 

STORY END 
~ EPILOGUE ~
Lizzi is pregnant/had a baby (translation was rough lol) either teacher Rö or Duke Rö (or both) are there as uncle and grandpar Bern has a new name and had been taken into Lizzis family before the wedding (he has a new name) they talk about the second prince and how they wanna back him up, about how the othet are doing managing their lives and how Katrin is the new Duchess Bernstein and will be doing a munch better job than her criminal father (i think that Girl went into a monastery with her brother) and everything is good (i was personally sad thaf Katrine didnt marry that dude thats alsways around her even in the manga thag upper class man that sat in her place that one time :( )

I REALLY HOPE THEY DONT CUT THE EPILOGUE

OMG! Thank you so much. I really did try reading the translation however that don't work out much. Thank you so much for the spoilers.

;) my pleasure

;) glad to help