Heh, somehow this episode managed to make me forget their age difference ans see them as a genuine couple...
I mean, young master is pretty mature here, and Mashiro feels more relaxed with him.
She doesn't tease him childishly nor do they call each other by those titles, calling themselves "you" more casually and naturally. I hope this change will remain in the future episodes, and that we'll see something else than those Past/Present confrontations which made me feel their relationship didn't actually grow naturally over time. Here we see it progress with yeras passing by, which is also really pleasant.