Online Boyfriend || KTH

A girl whose name is Min Y/n,a school student suddenly gets a Sms,
KTH : I love you.
Y/n : who is this?I think you got the wrong number.
KTH : no, Your name's Min Y/n.Right?
Y/n : H-How do you know?
KTH : I just know.

Who is that person and will Y/n save herself?

Start : 15 | 12 | 21
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