This is the first time they somehow made an allusion to the manga's title, right ?
I really loved the fact that Makio wanted to keep the song as a memory hehehe.
I was wondering last time, about the Scorpion, now that we even get the sign of the zodiac, I think the author refers to Asa's struggles because of her "nature" like for example here:
Scorpio Zodiac Sign
Strengths: Resourceful, brave, passionate, stubborn, a true friend
Weaknesses: Distrusting, jealous, secretive, violent
Scorpio likes: Truth, facts, being right, longtime friends, teasing, a grand passion
Scorpio dislikes: Dishonesty, revealing secrets, passive people
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Now, I don't know if Asa's birthday is between October and November, but she seems to be a scorpion