I don't remember if it was implied that the seme did have sex with that person before uke became his student then took multiple potions to help stem his sexual desire until uke was old enough/ wanted sex. Or if the seme drank potions the entire time and that the uke was being jealous. (But like realistically the seme is probably a lot older due to his immortality/youthfulness and it doesn't surprise me if he had a few sexual escapades before settling on the uke) Raws/spoilers wasn't very clear on that.
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This entire story doesn't make sense. It's very confusing, from miss understandings to what the heck uke you learned to kick ass but barely character development? And yo, seme needs some like logical pill or something but it's like all he thinks about is being possessive and not really cluing the uke in for any important decision making. The only reason why I read it is for the historical master & disciple sex scenes.
Read the spoilers and raws. Felt barley anything issues that happened between the two of them was push under a rug in a forgotten cabin that's actually 5 minutes away from the city. Read at your own risk. (⌒▽⌒)