Hi, nancy drew.
Thank you for your reply.
after reading the lyrics "this blue bunny" sounds strange to me
It is a good question.
But, even Japanese people do not know about that meaning.
There is no way except you ask the songwriter of that song.
In Japanese, that "blue" is not ordinary blue, but is the "bluish green."
That is blue like the sea.
Well, it seems that according to her sign language, she is singing as follows.
The part 1, 2 of this song is "the rabbit of (my) heart", and the last part is "the rabbit of (my) dream."
(Not a bunny but a rabbit, I think.)
But, probably, it is because sign language was not able to express the meaning of "blue."
In my opinion, I think that that "blue" expresses her "loneliness" (feeling that "I miss you").
If a rabbit is lonely, it may die.
possible