Tatsuya was born in 2007 to Kaito and Yukari Munemori. He has lived in Tokyo and is a big fan of games of the Digimon who became a target of merchandising by several businessman after the Digitaclysm. Tatsuya had been wishing to visit other countries for his whole life and also wished to become a member of the new generation of DigiDestined, but was afraid of his parents possible reactions to such thing.
Tatsuya is an active user of Facebook and is skilled in English language enough to make friends even outside of his home country, including Jason Storm. After he as offered as a chance to go as an exchange student into New York, he immediately took it in order to meet Jason in person and travel overseas for the first time.
During the night before his departure to go as an exchange student to New York, Tatsuya saw a dream of a girl and a Digimon named Renamon fighting against Lynxmon near a building that was on fire. On next day, he saw a mysterious light during his flight to New York, but no one else saw it. On the house of Jason Storm and his family, Tatsuya found a red device that looked like an unknown type of Digivice, later revealed as D-Ark.
After his first school day and meeting Kyle Lambert and Mei Yashida for the first time, he went with Jason and Kyle to show the device to a game shop owner named Steve who had no idea what the device was. But then, a cloud of fog that allowed the Digimon to Bio-Emerge sent a red Rookie Level Digimon named Guilmon into the real world. Tatsuya, Jason and Kyle also witnessed a Bio-Emergence of Gorillamon, during which they two other Tamers: Vera Neidhardt (who was the same girl from Tatsuya's dream) and Andrew "Andy" Conteh. While Vera and Renamon wanted to destroy Guilmon, like every other Digimon, Andy and his partner Terriermon tried to defend them. But Terriermon accidentally Digivolved into Galgomon and lost control if its powers, until Tatsuya and Guilmon were able to stop him.
During the evening and the next day, Tatsuya and his new friends were wondering about the meaning of his dream. They also met a small Digimon named Calumon were once again challenged by Vera and Renamon. They were later interrupted by the men from W.N.D.D. (Worldwide Netowrk of the DigiDestined) led by Harold Thompson. Thompson was a friend of Julius Conteh, Andy's father, and explained that the Tamers and the Bio-Emerged Digimon were played all along by an organization named Digital Revolution that sought to take over the Digital World to be used for the evolution of the mankind. Calumon was revealed a catalyst for the power of Digivolution and Vera's father Ian Neidhardt was revealed to be the leader of the Revolution.
When the Revolutionaries opened a Digi-Gate to bring several Digimon into the real world to be brainswashed, Tatsuya and Guilmon participated into the battle. Tatsuya quickly learned to use his Digimon trading card game cards to boost Guilmon's abilities and they defeated a brainwashed FlareLizarmon. But then Ian's attempts to bring even more Digimon mutated him into D.H.M. and three Ultimate Level Digimon Bio-Emerged. Tatsuya knew that he needed to make Guilmon Digivolve, but was afraid that things would go bad like in Terriermon's case. After letting go of his fear, he helped Guilmon to Digivolve into Growlmon by using a card "Digivolution Plug-In S" which was imbued with Calumon's power. Tatsuya and Growlmon helped Thompson and Reppamon (Champion form of Kudamon, Thompson's partner) to defeat a brainwashed Kumbhiramon, and after that Tatsuya and the other Tamers defeated D.H.M.
After the battle, Tatsuya was not recruited into the W.N.D.D. like the governments normally would insist, but made merely a consultant like the other Tamers. Keeping Guilmon and the other Partner Digimon hidden in an abandoned building in New York, Tatsuya, Andy and Vera occasionally visited the place and trained for future battles. He had also started a relationship with Mei, teaching her to play the Digimon trading card game.
One year later, Tatsuya had already returned to Japan. But when he ended his relationship with Mei, he had been too afraid to discreetly say his goodbyes to her. When the Tiger Deva Mihiramon Bio-Emerged near the Tokyo Skytree, he and Guilmon challenged him, but were badly outmatched. By using the mysterious Blue Card, Tatsuya was able to make Growlmon Digivolve into WarGrowlmon and defeat Mihiramon. But his status as a Tamer was exposed to the world and he was arrested. Guilmon was kept away from him and he had to tell the truth to his parents.
Tatsuya and Guilmon were freed by Thompson who took him to the United States to meet his friends and discuss about the threat the Deva posed to them. The Deva were claiming that they had come to reclaim something that was stolen. They didn't know what but they were no longer permitted fight without the permission of the Joint Chiefs of Staff. When they were given a permission by the President Gerald Johnson, the left to face Pajramon the Sheep Deva and Vajramon the Ox Deva, Tatsuya tried to use the Blue Card again, but noticed that it was missing. The battle was won when Andy got another Blue Card and Pajramon was defeated by Rapidmon (Terriermon's Ultimate form). But Renamon was captured by Vajramon, and the permission given to the Tamers turned out to be false, resulting the W.N.D.D. being terminated.
Tatsuya was later expelled from his high school in Japan, making his life even harder. He expressed his opinion to return to New York permanently. He was also a little bit jealous when Mei had befriended Wizarmon, one of Kudamon's friends. But his attention was taken somewhere else when he was taken to a room where Thompson's mentor Grigory Shatalov was in coma. Then, a holographic apparition of Shatalov appeared and explained that his mind had been separated from his body and was living in the Digital World. It was revealed by Lopmon (the Rookie form of the Rabbit Deva Andiramon) that Calumon and the Crystal Catalyst, the source of the Digivolution were one and the same. And the Deva planned to take Calumon back into the Digital World. A fragment from the power of the Catalyst had been imbued into the Blue Cards and they were given by the DigiGnomes who had also given the Tamers their D-Arks.
Then the Deva launched a new attack in Miami, Florida. It was also revealed that the real Predisent was dead and the impostor was Mahoragamon the Monkey Deva. The battle was almost hopeless until the Tamers received permanent Blue Cards to be used. Tatsuya and WarGrowlmon defeated Indramon the Horse Deva and combined their power with the other Tamers to defeat Vikaralamon the Pig Deva. Mahoragamon and Caturamon the Dog Deva, however, managed to capture Calumon and take him to the Digital World.
After the battle, Tatsuya and his family moved into New York. Wanting to know what was the new threat Deva explained to be fighting against, Tatsuya decided to travel into the Digital World once the new Digi-Gate Arch would be completed. Tatsuya and Mei also decided to forget their relationship until the truth behind the recent events would be found.
One year after the battle of Miami, Tatsuya and the other Tamers were finally able to reach the Digital World. But due to an unknown interference, Tatsuya, Andy and Susan Conteh (Andy's sister) were separated from others. When the group is reunited, Tatsuya is also informed that a Finnish card game champion Riku Arhinmäki is also in the Digital World, with his Partner Digimon Cyberdramon.
Tatsuya and the other Tamers are soon faced by Caturamon and Beelzemon, Impmon's Mega form who resembles one of the Seven Great Demon Lords. During the battle, Beelzemon kills Wizarmon, devastating Mei and infuriating Tatsuya. Tatsuya's anger influenced Guilmon and made him Dark Digivolve into Megidramon. Megidramon easily defeated Caturamon, but Beelzemon uses the coped techniques of the Deva to almost kill Megidramon who De-Digivolves into Guilmon. After coming to his senses thanks to a brief talk with a DigiDestined Troy Dawkins and Agumon, Tatsuya learns to Biomerge with Guilmon and become Gallantmon (Guilmon's true Mega form). Gallantmon almost kills Beelzemon, but Mei pleads Tatsuya to spare him.
The Tamers and Mercurimon, the Digimon who sent the Deva, are persuaded by Apollomon to understand that they must fight against the common enemy: D-Reaper, a malevolent multi-agent program who believes that humans and Digimon don't deserve to exist. While the other Tamers manage to avoid D-Reaper's first attacks, Tatsuya goes to find Mei who was missing. But when the Tamers return to the real world, Tatsuya is shocked Mei he saved was actually a fake created by D-Reaper.
When D-Reaper started to invade the real world as well, saving Mei became Tatsuya's top priority. That is why he separated from the adults and decided to fight D-Reaper by himself, only to be followed by the other Tamers. Fighting against ADR's (Agents of D-Reaper) wasn't easy, since the Tamers and their Partner Digimon were unable to Biomerge into Mega Level in the real world.
Soon, Tatsuya and the others are met by Edmund Harmon and Gia Avilés as well as their Partner Digimon Patamon and Tailmon. The two DigiDestined had been tasked to restore the ability of each Partner Digimon to Digivolve into their Ultimate and Mega forms. They also gave the Tamers an ability to Biomerge with their Partner Digimon in the real world. The Tamers are also joined by Beelzemon who wants to make up for killing Wizarmon, as well as Grani, a mechanical ship which acts as Gallantmon's mount.
After D-Reaper's main body and Mei's prison were located in the Core Layer of the Digital World, Tatsuya and Guilmon joined the final battle along with other Tamers, Apollomon, Mercurimon, Omegamon and Imperialdramon. When Beelzemon is wounded and Grani damaged, Grani's data is drained inside Gallantmon who changes into Crimson Mode. But the effect of the Red Card wore off earlier due to a programming error and the Partner Digimon were forced to De-Digivolve. Tatsuya and Guilmon, however, manage to use the data of the White Card to shut down D-Reaper. Tatsuya and Mei reconcile their relationship and he becomes an official member of the United Digital Activity Agency, the replacement of the W.N.D.D.
In 2044, Tatsuya and Mei were married and they had a son who joined Guilmon into the Digital World for the first time. Tatsuya knew that there will be a new threat one day, but was happy that they still lived in peace.
- Tatsuya is mostly based on Takato Matsuki since he has Guilmon as his partner and his initial personality is that he is a huge fan of the Digimon but realizes how complicated his life becomes after becoming a Digimon Tamer. His sense of justice is also strong and his crush on Mei Yashida is inspired by Takato's crush on Jeri Katou.
- When the Cinematic Sagas counterpart for a Tamer partnered with Guilmon was planned for the film series, Tatsuya's first name was initially chosen as the official name for the character.
|Characters in Digimon Cinematic Sagas|
|DigiDestined:||Troy Dawkins & Agumon | Seamus Maitland & Gabumon | Jake Thacher & Betamon/Gomamon | Miyuki Koharuno & Piyomon | Kevin Harmon, Tentomon & Armadimon | Edmund Harmon & Patamon | Dan Linwood & Veemon | Wei Xueqi & Wormmon | Gia Avilés & Tailmon | Nadia Coetzee & Palmon | Omegamon | Imperialdramon|
|Digimon Tamers:||Tatsuya Munemori & Guilmon | Andy Conteh & Terriermon | Vera Neidhardt & Renamon | Harold Thompson & Kudamon | Mei Yashida & Wizarmon | Jason Storm & Hagurumon | Kyle Lambert & Piccolomon | Susan Conteh & Lopmon | Riku Arhinmäki & Cyberdramon|
|Other characters:||Robert Harmon | Calumon | Impmon | Grigory Shatalov | Huckmon|