Duel Masters LOST is an alternative take on the 2022 Duel Masters WIN anime series that explores what would have happened if the protagonist, Win Kirifuda, had been defeated and lost his memories in the process.

One day, mysterious incidents occur frequently in Shinjuku City, Tokyo, where people's have suddenly disappeared. Half a year ago, Win Kirifuda, who woke up in this town, had lost all his memories. In his high school and part-time job he started attending on a whim, he couldn't fit in with those around him. He spent his days feeling frustrated, hanging out in the park at night with classmates such as Niika. Such daily life undergoes a transformation with the appearance of Crysta, a mysterious transfer student who claims to "know everything about Win." She says that they are engaged, but behind her, a dubious presence lurks. What is the truth behind the frequent mysterious incidents? What is Crystas's sudden goal? And what about Win's hidden past? A new story begins to recover the lost memories.—Duel Masters Wiki

"LOST" is an "alternate time story" that progresses at the same time as the current story of Duel Masters Win, and the Duel Masters LOST Tsuioku no Suishou manga depicts a never-before-seen world. It centers on 16-year-old Win Kirifuda - the protagonist of the Duel Masters Win anime - who has lost everything. He is then drawn into a battle to regain the world he once desired.—Anime News Network

Duel Masters LOST is an alternative take on the 2022 Duel Masters WIN anime series that explores what would have happened if the protagonist, Win Kirifuda, had been defeated and lost his memories in the process. Set in Shinjuku against the backdrop of a series of mysterious disappearances, Win's stagnant daily life begins to change with the arrival of a mysterious new transfer student named Crysta.—Crunchyroll News