Project work?...Nah! Childhood hangout!

Eventually in the library, Sansui finished his part and slept while Takahashi had a hard time calculating the problems but eventually managed to finish it anyway, she woke Sansui up and asked that if he was sleeping in which he replied in sarcasm "No dumbass I'm training for my funeral" Hearing this, Takahashi got slightly annoyed and told "Oh yeah? Might as well die now, right?" in which Sansui replied,"I would've died long back(mentions of the kidnapping incident). But I decided to stay alive for your sake in order to not make you lose hope for the promises we both made... Takahashi now regrets what she said and starts apologizing...Sansui told."Come on, don't apologize for small things, I am usually forgiving to the people I cherish, so you're like a diamond to me,"

Takahashi: Sure then, don't say I didn't warn you he-he *stomps on his shoe*

Sansui: *visibly annoyed* Ok, now why did you do that right now??

Takahashi: Not like these shoes are expensive anyway! *with a taunting smirk*

And they both started fighting verbally to the point they got kicked out in the library. In childhood, they either both exchange gifts together or fight for the most stupidest reasons, but it only made their bond grow stronger. In this current situation after they got kicked out in the library, they talked as if nothing happened and they didn't know time was passing by until they reached to their college campus, both waved goodbye and they went to their own dorms. Tomorrow it will be a surprise, a surprise that Sansui will not be expecting for the better...

But before the oncoming plot, we shall go back to the history professor's relation with Kageyama (Sansui's father)...

The history professor (Haruto) used to be Kageyama's dear friend, until one day Kageyama changed completely and decided to change his appearance and behavior ever since his younger brother Tokusa not only made his parents proud by achieving well in every competition including intellectual and creative skill, but also this made the parents resent Kageyama more for not being good enough. Kageyama decided not to meet anyone's expectations and did what he wanted to instead. Over time, Kageyama got into a popular group and mocked and bullied Haruto, and the one who enjoyed making fun of him the most was Kageyama himself. This led Haruto into confusion and hatred for what he did and had no other choice but to plan for revenge. Later on, Haruto got the job as a history professor and however got accepted into the same college as Kageyama's son Sansui, Haruto got to know about it when he was talking with the math professor and found the opportunity to instead making the father's life miserable, his son was the perfect target for Haruto's revenge to which he thought that the father will be miserable if he hurts his son instead.