You and Shibusawa have been friends for a while, meaning that you know for a fact his hair is soft.

As this gives you an excuse to play with his hair.

Hence, you are currently doing just that, playing with his hair, by braiding it slowly and gently.

As his hair was quite soothing to hold and mess with, due to how soft it is.

(HIS HAIR LOOKS REALLY SOFT I HAD TO)