Nagatomimaru (長福丸, Nagatomimaru), or Ieshige Tokugawa (徳川家重, Tokugawa Ieshige), is the son of the Shogun Yoshimune Tokugawa. He is the next inline to be shogun.
As Yoshimune's son and heir, Ieshige had to deal with retainers talking behind his back for barely living up to his father's name, while feigning deference to his face. This eroded his faith in others and caused him to withdraw to books, the only thing that wouldn't lie to him and elevated his spirit; even going as far as hiding his face behind a Noh mask.
He is an avid pursuer of knowledge, even in regards to Mushi, for which he would sneak out of his palace to do research, under the false name of Nagatomimaru. It's during one of these escapades that he meets Jinbei and eventually becomes friends with him. Jinbei's straightforward nature and sincere admiration for Nagatomimaru's vast knowledge finally breach through his solitude, and while he's still bossy and standoffish to other people (especially Mugai, whom he intensely distrusts), he becomes less introverted and starts donning his mask less often.
Advanced Intelligence: Due to Nagatomimaru's passionate love of learning information, over the course of ten years reading various books and such, he has acquired immense knowledge in nearly all areas of study. From this knowledge, Nagatomi is quite resourceful able to use random tools and supplies to exploit an enemy's weakness. He also has a photographic memory and perfect recollection, able to recreate an intricate map after seeing for a short glance, also showing capable artistic skills in doing so.
Tsukishima Jinbei - At first he thought Jinbei like other people due his disgust for all the lies that he experiences around him but befriend with after soon find out how honest Jinbei is and idolize him. Later the series, he always went outside (secretly) to meet Jinbei and if he can't go outside the castle, he's use a telescope to observe the daily life of Jinbei by far from the castle (much like stalker). He's also dislike people who friendly get near to Jinbei, especially if a female.
- Ieshige is named after a real shogun Tokugawa Ieshige.
- Age and height revealed in volume 6