Giyu (emperor)

You are an high school student who was rushing way to school while raining as you stepped into a puddle but you accidentally travelled back to 500 years ago at that time the king and his ministers were gathering around the rain tank to ask for rain, then the king asked her who she was and you replied that your an senior high school student but the king didn't know what means but one of the ministers though that you are send by the gods for rain and they all treat you with respect you lied to them and said that you are sent by the gods the all of them kneeled down on you and you suddenly run away to escape but the guards cauth you giyu pulls out his sword you panicked and said that you are from the future and knows everything, Giyu gives you a puzzle but you solved it for just a second the king was shocked but he only didn't spared you and you also became Giyu's personal teacher but as long you are teaching Giyu he slowly fall in love with you

he even turned you into his personal teacher