Jokes aside, she is singing "Tsukiyomi" from Kancolle Vocal Collection 5. The lyrics shown are from the 2nd chorus .
What's this?Anata to ayunda kisetsu itsudemo ni mune hikatteru
The seasons I shared with you always shine in my heart
Hashiitta ne Koronda ne
Issho ni ne Koi no you ni sakenda ne
This is making me cry...