In this Japanese name, Amakusa is his family name/surname. Shiro is his given name and Tokisada is his middle name
Shiro Tokisada Amakusa (天草 四郎 時貞, Amakusa Shirō Tokisada) is a recurring boss and playable character in the Samurai Shodown series, being an alternate portrayal of the historical figure of the same name.
The historical Amakusa led a Christian rebellion in the Shimabara region of Japan where the bakufu army crushed his revolt and executed him.
Though this series' portrayal of him bears similarities with the Amakusa in Makai Tensho, the developers haven't confirmed if he was particularly based on him. According to Gamest Mook, he was a possible candidate for the Samurai Shodown 64 lineup but was taken out due to time constraints. The developers of Samurai Shodown (2019) are aware that fans want Amakusa in the game, but due to the new installment taking place before Samurai Shodown his inclusion isn't possible. 
Prior to the events of Samurai Shodown, Amakusa is resurrected by the dark god Ambrosia; he uses the body of Shinzo Hattori (one of Hanzo's sons). His main plot involves him stealing the Palenke stone, which he intended to use to bring Ambrosia to the mortal world. Haohmaru prevents this from happening by defeating him.  Upon his resurrection in Samurai Shodown IV, his spirit splits into two halves: one good and one evil. Amakusa seeks his other half in order to regain his full power but was unsuccessful as his evil counterpart was slain by Kazuki in the same game but his good side lives on thanks to Shinzo.  
He's a mad and vengeful spirit, resurrected by Ambrosia as a being of destruction to put up a new world order. Once he is relieved of the dark god's possession, he reverts to his living persona as a kind and merciful soul of righteous constitution. He is a narcissist by nature, which is what originally lured him to Ambrosia's temptations.
True to the historical Christian Amakusa, he speaks of sin, mercy and salvation, especially in later appearances.
- Levitation - Amakusa has the power to levitate his weapon and other characters off the ground.
- Teleport - Amakusa can teleport himself.
- Multiple Attacks: Amakusa can deliver several slaps at once.
- Fire Projectile: Amakusa has the ability to project a fiery image of a demon.
Amakusa fights his opponents by attacking them with a levitating gem. He can direct the gem with an impressive range, able to smash his enemies from the air and ground level from nearly any distance easily.
At times, his gem may not compensate for opponents close to him so he also has hand attacks that often involve a multi-hitting slap attack. To confuse his adversaries, he may also teleport and hover above them before diving upon them with a damaging attack. He also projects fiery projectiles in the image of demons or electric balls to his foes, making him a formidable long-distance fighter.
He has slow jumping speed and can be laggy in the air, but possesses powerful basic attacks in exchange. Also, he can triangle jump.
Being up-close to your opponent can be a problem when playing as Amakusa, so he tends to play a mostly keep-away game, and relying on reflexes to attack or counterattack.
- Ankoku (Darkness) - Samurai Shodown
- Kyoutai (Madhouse) - Samurai Shodown III
- Movement to Tranquility - Samurai Shodown IV
- Crazy Behavior 1, 2, 3 - Shinsetsu Samurai Spirits: Bushidou Retsuden
- Eiji Yano - Samurai Shodown ~ Samurai Shodown IV, Nakoruru: Ano Hito kara no Okurimono, Samurai Shodown VI (Anthology Redub), The King of Fighters: All Star
- Yū Daiki - Samurai Shodown: The Motion Picture
- Marcy Rae - Samurai Shodown: The Motion Picture (English voice)
- Kaneto Shiozawa - Samurai Shodown Dengeki drama CD series
- Misuaki Madono - Shinsetsu Samurai Spirits: Bushidou Retsuden
- Takashi Ōhara - Samurai Shodown V Special
- Junji Majima - Samurai Shodown VI
- Show Hayami - Samurai Spirits Oni
- Ryotaro Okiayu - Ninja Resurrection
- Yasunori Matsumoto - Sins of the Sisters
- Samurai Shodown - playable in the Sega Genesis and SNES versions
- Samurai Shodown III
- Shinsetsu Samurai Spirits: Bushidou Retsuden - as one of the main villains
- Samurai Shodown!
- Samurai Shodown IV
- Samurai Shodown V Special
- Samurai Shodown VI
- Samurai Spirits Oni
- Samurai Spirits ~Kengou Hachiban Shoubu~
- Quiz King of Fighters - unplayable boss
- Samurai Spirits - Shimensouka (enemy character)
- Samurai Spirits - Makai Rineki
- Grandblue Fantasy
- The SAMURAI Kingdom
- Samurai Shodown Online
- Kingdom Story
- Kimi wa Hero
- Samurai Shodown Tenkadaiichi Kenkakuden
- The King of Fighters: All Star
- Samurai Shodown II - during cutscenes
- Nakoruru: Ano Hito kara no Okurimono
- SNK vs Capcom: Match of the Millenium - during Akari's super
- Samurai Spirits (pachinko)
- Samurai Spirits Gaiden: Cham Cham
- Samurai Spirits 2: Asura-Zanmaden (OVA) in Shiki's visions
- Pattern of his normal attacks changed in every game in he has appeared so far.
- His Polish lover was a tomboyish childhood friend who picked on him when they were younger. She grew up to be a fair yet strong lady. Apparently, he is beginning to forget what her expressions were like.
- When asked "The path of the sword is?", Amakusa's response is "Finding ways to atone for his sins." 
- Due to his largely effeminate looks, he was once mistaken for a female, evident in the English dub of the Samurai Shodown anime. His voice in Samurai Shodown VI seems to poke fun at this with a matching effeminate voice that borders actual femininity.
- He bears a deep grudge against the Tokugawa bloodline, the one responsible for his original death, as seen in one of the cinematics of Samurai Shodown. This is a callback to his historical inspiration. There are currently no canon-specific interactions however between him and the current Tokugawa in the series, Yoshitora.