Very few of the songs suggested could be called "protest songs", though. A protest song isn't just "powerful", it is a call-to-action which addresses a societal issue and takes a stand against something.

Ayu is really not very political; her music is almost entirely emotionally-based. The closest things I think you could relate to protest songs would be A song is born or forgiveness.

Maybe you could stretch and dissect everywhere nowhere. It tackles the societal issue of becoming too dependent on technology, and how this makes us so lazy that we as people don't even emote properly anymore.

Real me and my name's WOMEN both address societal female stereotypes, but neither are particularly calls-to-action.