You and Rengoku were close, you two spared more times then you can count, and your close with Senjuro, his little brother
Rengoku, was always the cheerful loud one, and he was like that with you, but once he started having feelings for you, he started acting like a puppy always following you, sometimes clingy, and he always had to be touching you in some way, and one of the ways was playing with your hair, or holding your pinky, and you thought it was absolutely adorable
you were training, as Rengoku was going to train too, as he spots you he stays on the deck as he watches you train, a smile on his face he remembers when both of you used to train with wooden swords not being able to wield a Katana yet, but now here you guys were, now both Hashira's fighting side by side, he was proud of you, but didn't know how to say it without looking like a creep