Coming of Age Day (成人の日, Seijin no Hi^?) is a Japanese holiday held annually on the second Monday of January. It is held in order to congratulate and encourage all those who have reached the age of majority (20 years old (二十歳, hatachi^?)) over the past year, and to help them realize that they have become adults. Festivities include coming of age ceremonies (成人式, seijin-shiki^?) held at local and prefectural offices, as well as after-parties amongst family and friends.

Coming of age ceremonies have been celebrated in Japan since at least 714 AD, when a young prince donned new robes and a hairstyle to mark his passage into adulthood.^[1] The holiday was first established in 1948, to be held every year on January 15.^[2] In 2000, as a result of the Happy Monday System, Coming of Age Day was changed to the second Monday in January.^[3]

National Youth Day is celebrated in India on 12 January on the birthday of Swami Vivekananda. In 1984, the Government of India declared and decided to observe the birthday of Swami Vivekananda (12 January, according to the English calendar) as a National Youth Day every year from 1985 onwards. To quote from the Government of India's communication, 'it was felt that the philosophy of Swamiji and the ideals for which he lived and worked could be a great source of inspiration for the Indian Youth.'^[1]

Swami Vivekananda's birthday (12th January, 1863)^[2], according to the Indian Almanac (Vishuddha Siddhanta Almanac) is on Pausha Krishna Saptami tithi, which falls on different dates in the English Calendar every year (generally in the month of January). This is observed in various centres of Ramakrishna Math and Mission in a traditional Hindu manner which includes mangalarati (a kind of worship practised in India, specially by Hindu people), special worship, homa (fire-ritual), meditation, devotional songs, religious discourses and sandhyarati (vesper service at evenings).