Takuya Endo is the second Another Den-O and the main antagonist of the "Another Den-O" arc (episodes 39 and 40) of Kamen Rider Zi-O.
Takuya's sister Sayuri was hospitalized because of an unnamed illness. After Sayuri died, Takuya blamed his sister's girlfriend Yukihiro for taking her out of the hospital and worsening her condition, even though nothing could be done to save Sayuri. Despite this, Yukihiro did not tell Takuya that Sayuri couldn't be saved at the wishes of Sayuri herself, who believed it wouldn't change anything if Takuya had known.
While at his sister's grave, Ora appeared before Takuya and asked if he desired the power to save his sister, handing him the Den-O Anotherwatch. Takuya used the Anotherwatch to become Another Den-O and was told by Ora to hijack the Den Liner, which had stopped for repairs at that time. After taking control of the DenLiner, Another Den-O tied up the Taros (besides Momotaros, who wasn't on board at that moment) and used it to travel to the date that Yukihiro took his sister out of the hospital.
Another Den-O attempted to attack Yukihiro, but was confronted by Geiz and driven outside. He later formed an alliance with a Mole Imagin that also sought to hijack the Den Liner and together they fought the Kamen Riders. Another Den-O was ultimately defeated when Sougo unlocked the power of Grand Zi-O and assaulted Another Den-O with various Rider Kicks, resulting in the Another Rider's destruction.
Later, the Takuya of that time, who had been told the truth about Sayuri's condition by Sougo and the others, met with Yukihiro and Sayuri at the spot they visited last and made peace with Yukihiro and his sister's fate.