- "It's not about what you can do, it's what you want to do."
- — Seisaku —
Seisaku is a tall man, with long silver hair that he keeps in a ponytail. Green tattoos decorate his face. While he played a Blade Brandier, his character wore a light blue fighting outfit. His Harvest Cleric has the same appearance, though the fighting outfit is replaced with a robe decorated in the same style. While on healing patrol he also wears a tinted helmet.
Seisaku is a very polite young man. He cares deeply for other people and wants to do something to help all the players in The World R:2. He is especially close to Tabby, who he seems to have romantic feelings for.
In the real world, Seisaku's player is a sixteen year old boy named Ryouta Noguchi. He is friends with Seiichi Yokoi, the player behind Hideyo.
Tabby was introduced to Seisaku after she ran into him while having a conversation with Kuhn. Kuhn invited him to join his guild Canard, but Seisaku refused his offer. Later, he traveled with Tabby to a field, where they had a conversation about the state of The World R:2. Seisaku stated that he hadn't joined Canard because he felt that it wasn't newbies who needed the most help, it was the mid-level players. Players who had only a little bit of power were the most vulnerable in The World R:2 because they constantly had to avoid being attacked by PKers. It was those players who he wanted to help, not the newbies.
Tabby admitted that she wished she could find a purpose like that. Seisaku asked her what she wanted to do, which caused her to state that she wanted to help Haseo and save Shino. Seisaku has since become a close friend of Tabby's. He has grown to dislike Haseo, and has tried to convince Tabby that she's wasting her time by going after him.
Later, with encouragement from Tohta, Tabby decided to use her Guild to help other people. Seisaku agreed to help her and became her first new member, creating a new Harvest Cleric to aid her efforts. He convinced his real life friend Hideyo to join as well and together they formed a sort of super sentai healing team.
However, after being PKed in the midst of a battle between Haseo and TaN's former members, Hideyo becomes angry and pulls a reluctant Seisaku from the guild. After speaking to Tabby shortly afterwards, he decides to join Hideyo in making their own healing guild. He is seen at the end of the series recruiting players for his new guild with Hideyo.
In the .hack//G.U. games, Seisaku is now a Tu Tribe Harvest Cleric who goes by the nickname "Heal Red". A founder of the guild Medic Union he acts as its unofficial Guildmaster. During the AIDA Server incident he and several other Medic Union members were trapped inside of The World. Following the incident he began searching the forums, looking for other people who had shared his experience. Still infatuated with Tabby he questions Haseo of her whereabouts whenever he meets him.