Well done MiHoYo.
And we get three flavors of Yae in this 1 letter too just like Ei's favorite dango. In part 1 you've just got that troll. Yae guilts you into thinking you forgot her birthday only for it to be a double troll since it isn't her birthday but you forgot the birthday of the Almighty Narukami Ogosho. How dare you! 
Then part 2 is more Ei trolling. At this point it just seems cruel. Way back before Inazuma was even on the horizon we knew more or less that Ei would be very immature. Then we got her Character Quests where she says things and reacts to things in such a blunt way. And there are some very typical things like writing a letter about your own birthday that shouldn't require much thought but our poor little Raiden Shogun couldn't figure out what to say. I don't know but I get the biggest Bakarina vibes out of her. She even has a sweet tooth lol
And it turns out she's not even the only ditzy Beelzebub in fiction. Introducing As Miss Beelzebub Likes!
And to think her voiceline for Itto is "who?" These two are a perfect pair. 
Brawn with barely any brains lol
Ehe but I digress. Part 3 sounds like a protective side to Yae. We're only allowed to tell her "happy birthday" no more no less. And here I thought Sara had the tsundere role. Maybe Yae knows about Aether's ever-growing harem. Then again it could just be that Yae already has Ei's love life planned out and if we got in the way of that it would ruin her fanfics.
MiHoYo planned that troll so well. Just a day off anybody would be forgiven for getting that wrong and falling for Yae's troll. On the other hand Yae's letter for herself is a full on tease!
But I mean come on. She wants to see our reactions in person? What do you take me f-
I'm not ashamed to admit I teleported to Narukami Shrine after this. Just on the off chance she was there..... 
She wasn't....
Tips and Tricks from a Super Casual Genshin f2p
