Before the story starts

So this is the second book of "My sister's best friend" I suggest reading that first or this story won't make sense.

So all the main characters (besides Sayuri) are all graduated from highschool and in college, Kokichi and Shuichi are friends again but Rantaro gets a bad feeling in his gut when Shuichi is around.

Kokichi believes he actually changed. One night when Shuichi and Rantaro are alone Shuichi has a little talk with Rantaro about his future with him and Kokichi.

Will Rantaro be able to get Kokichi away from Shuichi in time before he actually does anything, or will Kokichi not believe him? Read to find out!