Sakamoto Tatsuma (坂本 辰馬 Sakamoto Tatsuma ) is the leader of the commercial entity by the name of Kaientai, which operates from a flying ship that traverses the galaxy for business opportunities. Labeled a 'natural-idiot', Sakamoto was one of the Samurai that fought alongside Gintoki in the Joui Wars.
While fighting in the Joui wars with Sakata Gintoki, Katsura Kotarou, Takasugi Shinsuke and other samurais, he dreamt of traveling through the galaxy in a spaceship rather than staying on this small planet and spent everyday watching his comrades die one by one. He tries to seek a way that both human and Amanto can benefit from instead of meaningless death for everyone. He asked Gintoki to join him on his trip to space, Gintoki encouraged him to go, saying that earth was too small for Sakamoto, but Gintoki refused the offer and decided to stay on Earth as he still likes this planet a lot. Sakamoto eventually broke away from the Joui movement to pursue his dream, with great commercial success.
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His too positive attitude sometimes lead him into all sorts of trouble as he tends to dismiss bad things as just 'imagination, a-ha-ha-ha-ha'. He acts even more stupid than Katsura, with Gintoki often saying that he is a "no brain idiot".
Sakamoto does, however, show an excellent ability in giving inspirational speeches and is also a brilliant negotiator when he needs to be, convincing the entire Renho race to turn on their leader.
He loves spaceships, but often gets weak and downright ill when he's actually on one. 
Strength & Abilites
Master Swordsmanship Specialist: He displayed leadership qualities when he was willing to sacrifice himself to save others, being held captive by a desert alien.
In the Joui War, he made a name of himself as a skilled swordsman but after the war he uses pistols instead.
His main strength would be, however in making deals and trades. He was able to buy off the entire Renho Tribe to Kaientai's and Yorozuya's side during Renho arc.
Friends & Allies
- Sakata Gintoki: Much to Gintoki's annoyance, he persistently calls Gintoki "Kintoki" and often gets beat up by Gintoki for this reason, much like Gintoki calls Katsura "Zura",It is shown that he knows Gintoki's name in the past. He states that it's because Gintoki was on the earth supporting him, he was able to go far away chasing his dreams. His lightheaded behavior is also a great source of irritation to Gintoki, who alongside with Kagura gives Sakamoto a trashing once in a while.
- Mutsu: His overly affable nature is also less appreciated by his number 2 commander of Kaientai, Mutsu who have to constantly track down her wanderlust leader whose movements are totally unpredictable.
- Katsura Kotarou: They have known each other since Jouishishi war. Even after Sakamoto flew in the space they are shown to be in good terms, because Sakamoto gave Elizabeth as a present for Katsura.
- Oryou: Sakamoto is in love with Oryou, Otae's friend Oryo briefly mentioned a man named Sakamoto being clingy to her in episode 36. She is a hostess working at 'Snack Smile', who would eventually end up kicking him at his crotch every time Sakamoto jumps onto her and in an anime original (episode 57), the crew finds Sakamoto asking Oryo to marry him, only to get rejected with a swift kick where it hurted.
In Lesson 13 he was first seen in a flashback during the joi war and on Lesson 20 he was mention by katsura that he bought Elizabeth, an Amanto space creature as a gift for Katsura Kotarou. In Lesson 26 he made his first appearance when he going on a trip to space and met up with Gintoki once again.
Memory Loss Arc
Sakamoto fills the Yorozuya and Katsura in about the Renho invasion that involves Elizabeth! On his spaceship, he takes them to the Renho's planet. He helps the group to stop the invasion and defeat Dark Vader. Later he plays Uno with Katsura.
Patriot Reunion Party Arc
- Based on Sakamoto Ryoma 坂本龍馬 of the Bakumatsu period who was an imperial loyalist. Another way to pronounce the "ryou" kanji in Ryoma's name is "tatsu" (kanji means "dragon"), but Sorachi-sensei cleverly uses a different kanji to achieve the same results. At one point, Ryoma envied the west for their power and technology but eventually became familiar with them. Though proficient in Kendo and was a samurai, he preferred guns over the sword. In Gintama, Tatsuma is the leader of the Kaientai, which is also the name of the first modern corporation in Japan that was founded by Ryoma. Ryoma was married to Oryo.
- Whenever Sakamoto tried to ask any women to date him all the women would say "no thank you" in English
- ↑ Sorachi Hideaki. Gintama. VIZ media, Vol. 4, Lesson 26, p. 20.
- ↑ Sorachi Hideaki. Gintama. VIZ media, Vol. 4, Lesson 27, p. 17.
- ↑ Translated from 空知英秋 Sorachi Hideaki, 銀ちゃねる! Gin Channel! (Gintama Official Character Book), 集英社 Shueisha Jump Comics, page 134.
- ↑ Sorachi Hideaki. Gintama. VIZ media, Vol. 4, Lesson 26, p. 21.
- ↑ Sorachi Hideaki. Gintama. VIZ media, Vol. 4, Lesson 27, p. 12.