You know...This is not actually NTR since MC's childhood/best friend is not in a relationship or dating the random Student president guy...It kind of similar to NTR though. The correct term would be BSS. If they were dating and MC had stolen her childhood friend away from the student prez or stolen the student prez away from her childhood friend then yes 100% NTR.
BSS (Rare term used by some characters in manga/ sub-genre of NTR like situation)- refers to a situation where someone is jealous or upset that someone else ended up with someone they had a romantic interest in, but the jealous party has no actual claim or right to be upset. (Example like 2 close childhood friends but one of them either a girl or boy ends up dating someone else later due to the other not confessing and keeping their feelings hidden.)
(bokuga sakini suki datta no ni), translates to "I liked them first" or "I liked them before". It describes a feeling of jealousy or resentment when someone else gets the person you were interested in, even though you had no relationship with them.
No one probably fking cares but eh...This is for those who want to know the proper correct accurate term to describe this situation.
Now thoughts on the 1st chapter...I really really just hope MC just does the silly seduction route for her friend instead of any very very questionable sexu@l harassment/touching stuff/situation happening even while her friends is protesting against it and being uncomfortable....Hopefully MC's best friend/childhood friend is actually Bisexual instead of just 100% pure straight...Because then MC can only give up or go down the dark corruption route...We can only wait for 2-3 more chapter to see where the author will choose which route MC will go.
Like kabedon (Wall-slam) tactic, lift her chin up flirt tactic, teasingly hand rub on wrist or arm or etc. etc. etc.