Let me just quickly summarize the last few episodes

setting is the same virtual game world

Our main character "Asuna" met a girl named "Yuuki" through a dual and helped her clear a dungeon boss with her friends

When Asuna got denied further communication from Yuuki, she found out Yuuki has final stage aid and have been in bed for 3 whole years

Since then, Asuna used the terminal machine made by Kirigaya

to let Yuuki enjoy the real world, everyday Asuna carried it to transferred vision and sound between Yuuki

in the end, Yuuki lived through the full 3 months of life that have been announced

now, I really want to talk about the connection between the 3rd ED song and the plot

the name of the song is "シルシ" which means "sign/proof" I can't think of any better word due to my poor English

the first person word used in the lyrics is "ボク" which is also what Yuuki used to call herself

"ボクが生きたシルシ" translates to: the proof/sign of my living

there are two signs/proofs of Yuuki has lived in this world we can tell from the plot

first, the reason why she wanted to clear the boss is to have her and her friend's name listed in the huge stone board

second, her original sword skill - "mother's rosario" that was gifted to Asuna

流れてく時間(とき)は容赦無く　いつかボクらをさらってくから - the flowing of time will eventually tear us apart with no mercy

represents her disease is taking her life away as time passes

this one is pretty straight forward to understand, there are other parts of the lyrics also link to the story and I'm not gonna talk about all

when I first listened to the song I was only enjoying the melody but once I knew the story

this feel carried out by this synergy between the plot and the lyrics has stunned me

I love songs that have connections to the stories, in this case I think it is very nicely done

here is a link to full lyrics if anyone interested - http://eudemon.org/lyrics.html/_/%E3%82%B7%E3%83%AB%E3%82%B7-r186