I'm a librarian who loves anime, manga, and reading a wide variety of genres.
Playing against Isumi helps Hikaru realize that Sai is now in his Go - if he wants to see Sai, even just a shadow of him, he must play. And so he does, and proceeds to win. There are rumors of a Japan-China-Korea Junior Cup, and players like Akira, Hikaru, and Ochi would be Japan's best chance. Meanwhile, Hikaru has his first match against Akira in two years and four months.
(show spoiler)
Oof. This is technically a slow volume, and I got a bit tired of older dudes talking about the up-and-coming youngsters, but the beginning was great - seeing Hikaru cry and realize he must play in order to see Sai (if I were Isumi, the way Hikaru was acting would have made me assume there was a death in Hikaru's family). So was the ending, with Sai silently passing his fan on to Hikaru.
I loved that Akira could see Sai in Hikaru's playing style but also appreciate Hikaru as his own player. He's no longer chasing after Hikaru because of the player he thinks he is (Sai) but truly seeing him as he is. If I remember right, this is where the anime ended (not counting the special), and it's a nice stopping point for those who liked Hikaru and Akira but also really liked (and really miss) Sai.
(Original review posted on A Library Girl's Familiar Diversions.)