Slum Online tells the story of Etsuro Sakagami, a college freshman who is obsessed with playing a beat'em up online MMO called Versus Town. Versus Town, as it is rendered in the game world, is this sort-of barren city where people log-in with their tough-guy avatars and beat the shit out of each other in stylized martial arts combat. It's like Grand Theft Auto, but no guns allowed, no crimes to be committed, or missions to carry out, just brawling. There's an arena where players go to win championships and have the official title of ultimate winner bestowed upon them. Etsuro's avatar is a karate ace named Tetsuo, and he's battling his way to the top.
But something strange is happening in Versus Town. A rogue avatar who comes to be called Ganker Jack is roaming the virtual streets taking on all comers. Ganker Jack doesn't fight in the official arena, but he's gaining unofficial rank as the toughest brawler in the game. His MO consists of challenging highly ranked fighters while wandering the virtual back alleys. No one knows who this guy is. Maybe he's some kind of AI. Tetsuo becomes obsessed with tracking him down, finding out who he is, and besting him in single combat.
In meatspace, Etsuro is a desultory student, but he catches the fancy of fellow freshman Fumiko, who is much more serious about her studies. The book alternates the virtual saga of Tetsuo's quest for ultimate championhood with Etsuro's somewhat listless dates with Fumiko in the gaudy, lonely Shinjuku district. Fumiko's obsession is cinema, an earlier, cruder form of virtual reality. Etsuro doesn't watch movies. Versus Town takes up all his memory capacity. It's a little mysterious why Fumiko is attracted to Etsuro. Maybe she sees this young man as a project. Or maybe she finds him non-threatening and this appeals to Fumiko, who's kind of a shy, bookish person. Etsuro and Fumiko's amusingly chaste real world relationship plays counterpoint to the virtual blood and thunder of Versus Town
Slum Online is an absorbing, clever, mellow read. The overall flavor of it is a mix of light comedy and existentialism. The comedy comes from Etsuro and Fumiko's humane, yet goofy, relationship, and the existential part comes from Etsuro's alter-ego Tetsuo as he grimly battles to prove himself in Versus Town. Along the way, Etsuro proves himself surprisingly insightful about his obsession. For example, in Versus Town some players go to great lengths to role play their avatars: typing text bubble speech "in character," engaging in virtual consumption of food and drink, affecting elaborate body language and costuming. Etsuro/Tetsuo finds this all rather risible. He's there to fight, to become the best, not get caught up in a Second Life-esque identity fugue.
Sakurazaka also pulls off something rather surprising: he makes the online brawling quite exciting and he quite clearly explicates the complex gaming mechanics of Versus Town's fighting styles and physics engine. This is important to understanding Etsuro/Tetsuo's existentialist obsession with mastering Versus Town. Etsuro/Tetsuo seemingly sees through the artifice of the role play aspects which ensnare other players, and keeps his focus on the control pad and the monitor.
Or is Etsuro becoming ensnared in another kind of illusion?
There are also some intriguing twists and turns to the story which are best left unrevealed. Slum Online is an engaging, fun, mellow, but occasionally intense foray into the head of a young man whose consciousness is divided between the real and the virtual.