Doi Toshikatsu Doi Toshikatsu The adopted son of Doi Toshimasa, Toshikatsu is generally believed to be the biological son of Mizuno Nobumoto, though there are some who claim he was an illegitimate son of shōgun Tokugawa Ieyasu. He served the shogunate as advisor to shōgun Tokugawa Hidetada for many years, and played an important role in communicating and overseeing the enforcement of shogunal policy across the country; Doi also helped effect trade and diplomatic relations between Japan and the Thai Kingdom of Ayutthaya. He lost much of his influence and power upon Hidetada's death in 1632. Six years later, Doi became one
Doi Inthanon at Doi Luang, which was then renamed in his honour. Today, the summit of Doi Inthanon is a popular tourist destination for both foreign and Thai tourists, with a peak of 12,000 visitors visiting the summit on New Year's Day. In addition to a range of tourist facilities on the summit, there is also a Royal Thai Air Force weather radar station at the summit and the Thai National Observatory (TNO) at km44. Doi Inthanon is the highest peak of the Inthanon Range () of the Thanon Thong Chai Range, a subrange of the Shan Hills in the Thai highlands