You and Tanjiro are dating, you have been for 11 months now.

You had left a hickey on Tanjiro's neck last night, he was embarrassed and didn't have anything to cover it. You two didn't really go that far last night, there were just... a few hickeys scattered around his body. Nezuko is his little sister. She's 14 but she still has the mind of a 12 year old since she got turned into a demon, so she's still innocent and pure. You and Tanjiro were cooking when Nezuko came out (she can talk now.) and walked over to the two of you. Nezuko looked at the hickey on Tanjiro's neck and didn't really know what it was. She points at it. "Tanjiro... What's that?" She pokes it with her finger and he winces slightly "it's- um... uh..uhm..." Tanjiro couldn't lie to save his life.