The katana, being a traditional Japanese sword, is primarily associated with Japanese martial arts. Several martial arts disciplines focus on the use of the katana and incorporate its techniques into their training. Here are some notable martial arts that utilize the katana:

1. Kenjutsu: Kenjutsu is a comprehensive Japanese martial art that focuses on the use of the sword. It encompasses various styles and techniques for wielding the katana and other traditional Japanese swords. Kenjutsu emphasizes both solo and partner drills, forms (kata), sparring, and principles of strategy and timing.
2. Kendo: Kendo, meaning "Way of the Sword," is a modern Japanese martial art that evolved from traditional kenjutsu. It primarily involves sparring with bamboo swords (shinai) while wearing protective armor (bogu). Kendo practitioners study kata and engage in competitive matches, emphasizing correct form, spirit, and strategy.
3. Iaido: Iaido is the Japanese martial art of drawing and quickly striking with the katana from a seated or standing position. It focuses on precise and fluid movements, mental focus, and the development of situational awareness. Iaido practitioners perform solo kata (forms) to train in the correct execution of drawing, cutting, and resheathing the sword.
4. Battojutsu: Battojutsu is a Japanese martial art that specifically focuses on the art of drawing and cutting with the sword in a single, fluid motion. It emphasizes speed, accuracy, and timing in executing decisive strikes. Battojutsu often includes the study of specific cutting techniques and practical applications.
5. Shinkendo: Shinkendo is a modern martial art founded by Toshishiro Obata that integrates traditional samurai swordsmanship techniques with practical combat applications. It emphasizes the study of kata, sparring, cutting exercises, and the proper use of the katana in realistic scenarios.

It's worth noting that while these martial arts focus on the use of the katana, they also incorporate principles and techniques that can be applied to other weapons and empty-hand combat. The study of katana-based martial arts provides practitioners with a deep understanding of Japanese swordsmanship, historical traditions, and the development of discipline and focus.