Toyonaga 【豊永】5 The Japanese surnames etymology dictionary.
① Kumamoto-ken Tamana-gun Nagasu-machi Origin of belly red (Haraka). A place name with a record in the notation of "鰚" during the Warring States Period. The place name was also written as "Hara" and "Haraga". Kumamoto-ken Kumamoto-shi Chuo-ku Honmaru was in the Edo era at the Kumamoto clan in the Clan office.