Boys & Girls of course. it seems that she always sing it in every concert she held (arena tour and cdl) and the only song that ayu always ask the audience to sing along.

SEASONS I think.

M and M Pv!!!

I think that's where ayu get all her die hard fans from..... :love....

I think that's the PV and song which got me so attracted to ayu....

for me. Hanabi~episode II~

for everyone else. M,Surreal,Evolution,Unite!

for AYU!!!!!! boys & girls, and who...

and YES EVIDENCE SUPPORTS THIS!!!!

im right, PERIOD, (you'll get over it)........

Definitely:

M - SURREAL - evolution

i think a tie betwen boys and girls and step you.everyones enjoy it!

prolly B&G or an audience song.

And Then or Heartplace.

It defines how Ayu thinks and how she lives her life, IMO.

I think M is a pretty good description, although I think her concert staples like Surreal, Boys&Girls, UNITE, Evolution, and ballad like Who... are also probably songs that describe her pretty well.

Lyrically wise I think Seasons for her earlier days, nowadays probably Real Me or Heartplace, or if it's brighter Blue Bird or Fairyland.

what do u mean by ultimate?
if u mean a song that represents ayu best..
lets put it this way. if the jpop music industry decides to do a documentary tribute to ayu, i think theres no doubt that the songs they'll choose for it are:

M - surreal - evolution - seasons - boys & girls - a song for xx and maybe Who..

but if i were to choose 1, i think it would be evolution.

M / evolution

Its either Boys and Girls or Who... there are other great songs but Boys and Girls and Who... just rock! XD