Weed

Weed is a videogame company in the Toaru Majutsu no Index universe. It is the creator of the successful Gekisho series of fighting games, but have recently been in decline. The company is also notable for having a school - Zassou Academy, a school dedicated to training people into becoming videogame developers in Academy City.

Poltergeist Arc
The videogame company is mentioned and referenced several times during episode 17 of the Toaru Kagaku no Railgun anime adaptation. Here, they are stated to have been in decline recently. During this episode it is revealed that their last Gekiso series videogame, Gekisho 9, is fairly old and that Tessou Tsuzuri (a fan of the videogame) wonders if they are going to release the next installment of the series, and later declares to Kounoe Haruki (who recently defeated her in a game of Gekisho 9, by using her own favorite character) that she would definitely beat him when it comes out, which Haruki takes notice.

Later in the episode, it is revealed that Haruki has transferred to Zassou Academy, implying that he would study there to become a videogame designer; this delights Tsuzuri upon hearing that he enrolled into the school that was funded by Weed, the company that made Gekisho series of games.

Trivia

 * The kanji for weed is 雑草, which means Zassō; this is a reference to Zassou Academy, the school that the company founded.