So popular as a fast food is beef on rice that the ¡°gyudon war¡± waged by its top three vendors ¡ª Sukiya, operated by Zensho Holdings Co., Yoshinoya of Yoshinoya Holdings Co. and Matsuya, run by Matsuya Foods Co. ¡ª is a frequent media topic.

Following are some questions and answers about the beef bowl battle.

When did the gyudon war start heating up?