Masamune Dan

"There are no continues for those who die frozen in time. He is trapped in the moment of death... permanently."

- Masamune after killing Lovrica Bugster. "The human known as Masamune Dan has ceased to exist. I am an existence with the powers of both Cronus and Gamedeus. The overseer of Kamen Rider Chronicle... and the True Final Boss."

- Masamune after absorbing the data of Gamedeus.

Masamune Dan is the founder of Genm Corp and primary antagonist of Kamen Rider Ex-Aid, having manipulated the events of the series to further his own goals. His ultimate objective is to become the controller of everybody's lives by trapping everyone within Kamen Rider Chronicle.

He was portrayed by Hiroyuki Takami.

Personality
Though he keeps up the guise of a friendly and benevolent businessman, Masamune's true personality underneath is that of a self-centered and manipulative sociopath who cares for nothing but his own goals, being willing to kill thousands of people in order to achieve them. He addresses each of the Kamen Riders and Bugsters by the Rider Gashats they use or in the game they originated from, viewing them not as living beings but as products of the Genm Corp and even refers to killing them off as "discontinuing a product".

For the first half of the series, Masamune keeps up the facade of a well-meaning CEO and father while he is behind bars and Kamen Rider Chronicle is in development. However, after he is released from jail and his plans start to come to fruition, Masamune reveals himself to be a tyrannical control freak who believes he has the right to control everyone's fates and is willing to do whatever it takes to see the end result of his goals, including resorting to underhanded and deceitful tactics.

Even after he has been defeated, Masamune clings to his belief that he is the controller of everyone's lives, and kills himself purely out of spite to preventing the victims of Kamen Rider Chronicle from being saved.

A more humane side of Masamune was explored in Another Ending trilogy, where it is revealed that Masamune was once a loving man who genuinely cared about his wife, before he eventually turned insane because of her infection of Bugster virus. He was also horrified by Kuroto's plan and insanity, and he would stop him no matter what the cost. However, Masamune still refuses to show remorse over his manipulation over Kuroto. Instead, he only curses his son, wishing the latter was never born.

Discovering the Bugster Virus
16 years ago, Masamune Dan learned of the existence of the Bugster Virus from his son, Kuroto Dan, who discovered it after it emerged from the Y2K crisis. Unbeknownst to everyone but himself, Masamune infected himself with the virus to develop an antibody for it within him.

After his son caused Zero Day and pinned the blame on him, Masamune willing took responsibility and allowed himself to be incarcerated in order to absolve him of guilt for the events that would follow, letting Kuroto step up to become CEO of Genm though, unbeknownst to him, his father was secretly using him to further his own goals.

Release
Masamune was eventually released from prison, allowing him to retake control of the Genm Corp. He soon showed his true colors to the Kamen Riders, revealing that his incarceration and Kuroto's succession of him had all been part of his plan.

Masamune blackmailed Hiiro Kagami into turning to his side with Proto Drago Knight Hunter Z, which had his girlfriend, Saki Momose, sealed inside of it. After much reluctance, Hiiro accepted the offer and betrayed Emu and Kuroto and prevented them stopping the Pause ability of Cronus.

With Hiiro's assistance, Masamune revived Kiriya Kujo so he could become observant for the players of Kamen Rider Chronicle and prevent the doctors from stopping its progress. However, reviving Kiriya turned out to be Masamune's biggest mistake, as Kiriya revealed that his true purpose was to make an opening so Emu and Kuroto would create a new way to defeat him.

Cronus was later defeated by Ex-Aid Muteki Gamer. Angry at his defeat, Masamune forced Hiiro to control Taddle Legacy, threatening to kill Saki for good.

Final Battle
Following the failure of his scheme to use Gamedeus to instigate another global pandemic, Masamune finishes off Gamedeus and absorbs his remains into his body, turning himself into Gamedeus Cronus. However, the Riders all revert back to Level 1, allowing them to separate Masamune and Gamedeus, with Parado sacrificing himself to destroy the latter with the Doctor Mighty XX Gashat.

Masamune then fights against the Riders as Cronus. While holding his own at first, Cronus ends up being overwhelmed by the Riders once they switch to their Level 2 forms, with Emu delivering the final blow. Defeated, Masamune kills himself out of spite to prevent any of the eliminated players from being saved.

Kamen Rider Ex-Aid Trilogy: Another Ending
Masamune appears in Another Ending trilogy as a supporting character. After his demise, Kuroto Dan instigated his escape plan and worked with Saiko Yaotome, who is in fact the daughter of Michihiko Zaizen aka Dr. Pac-Man, the deceased former leader of Next Genome Institute. They brought Masamune back to life as a Bugster using his data, so that they would extract the Bugster Virus in Masamune and bring it into its manisfection, resulted in creating Black Parado in process.

During Saiko's experiment, she took then Poppy to a clothes store which Masamune Dan had also taken his wife Sakurako Dan just prior to the birth of their son. Poppy wore the dress in the same style which Saeko once dressed, and had a vision of Masamune happily taking photos of his wife.

Meanwhile, after creating Black Parado, Kuroto tied his imprisoned father on a piller with Level 0 program. Kuroto revealed his plan in front of his father and spitefully humilated him, forcing him to atone for his crime of exploiting him. However, much to Kuroto's shock, Masamune only claimed that the only past deed he ever regretted was the birth of Kuroto. Disappointed, Kuroto later left his father to rot after absorbed the data of Black Parado and created the gashat of God Maximum Gamer Level 1000000000 as a result, before returning the Buggle Driver II to his father.

Determined to stop his son's mad plan, Masamune tried hard to break free and managed to transform into Kamen Rider Cronus once more. After defeating a Zombie Player, Masamune teleported himself to Kuroto's game area, right on time to rescue a near-defeated Kiriya. Disgusted over Kuroto's madness, Masamune decided to discontinue Kuroto by himself. Kuroto tried to convince his father into give in and restore every victims datas back to normal - datas that have been restored because of the game's reset. However, Masamune refused. Kuroto then asked if he never cared about Sakurako anymore, but Masamune said he would always remember her and had moved on from her death.

Then, they started to battle, but Kuroto soon defeated his father when Masamune's Pause proved to be useless against Kuroto's game area set in universe. Kuroto soon left after defeating his father, leaving the latter to die. In his final moment, Masamune asked Kiriya to trust him for the final time, saying he must stop Kuroto and still believing his son should never be born. After that, Masamune died once more and became datas within Buggle Driver II once again.

Kamen Rider Zi-O
In Kamen Rider Zi-O, due to the alterations of the timeline by the Time Jackers, Masamune Dan became just an ordinary CEO rather than the maniacal control freak he was in Kamen Rider Ex-Aid. He was killed in 2016 by Kuroto Dan so he could usurp his father's power.

Trivia

 * Masamune Dan shares some similarities with Tenjuro Banno from Kamen Rider Drive. Both played a role in the creation of the villain factions of their respective series, are opposed by their own sons and are their series' true main antagonists. Both also possess massive god complexes, though Masamune is more composed for a villain in contrast to Banno's psychotic personality; although Masamune becomes more mentally unstable and paranoid than his own son after suffering his first defeat by Emu.
 * Masamune Dan's theme song as Kamen Rider Cronus is JUSTICE, which is sung by his actor, Hiroyuki Takami, who ironically also sings Kuroto Dan's theme song as Genm. It should also take into consideration that Hiroyuki Takami is the lead singer of a Japanese pop duo known as "access".