Ekiden (駅伝) is the term for road relay in Japanese, the two kanji meaning “station” and “transmission” in reference to the posts that were set up at regular distances along the Tokaido during the Edo period. The first competition was held in 1917—a gruelling 500km race from Kyoto to Tokyo—and today there are numerous competitions up and down the country, but the most famous one is undoubtedly the Hakone Ekiden.
It is held on 2 and 3 January each year and begins and ends in front of the head offices of the Yomiuri Shimbun (the newspaper which sponsored the first event and whose then Social Affairs Department chief editor coined the term “Ekiden”). University teams of 10 competitors, run 107.5km on the first day to Lake Ashi in Hakone, and 109.6km on the second (each split into 5 sections) to return to Tokyo. The first Hakone Ekiden was held in 1920 between four universities, but now the competition—which is televised and followed widely—sees about 21 universities compete (the top 10 from the previous year’s race are given automatic entry to next year’s event). Aoyama Gakuin, Toyo University, Waseda University, and Komazawa University have been strong in recent years.
The event is well-organised and tens of thousands come out onto the streets to cheer the runners on. You can find the course on the official site. Some kind soul has also added these maps of the day 1 and day 2 route. The race starts at 7am and ends around 14:00-14:30 each day.