I woke up this morning around 9am to find 'あいこからの手紙' (a letter from Aiko) on the screen of my TekuTeku Angel. It was sad that I didn't get to see if there was any 'leaving' animation or anything like that at midnight, but I was excited to read the letter. I wrote down everything as I read it just in case it didn't let me read through it again. Here is the letter with translations done by me:
A letter from Aiko
You've given us many walks together
so truly, thank you.
From here on, I will look after and protect you!!
Thanks to you I've become an angel
but to me, you are the angel!!
I will not say goodbye.
Let's meet again, okay!!