The game appears to take place between Season 1, and a point in Season 2 when the Senshi have their memories restored, and there are no enemies. So perhaps after defeating Ali and En, but before Chibi Usa appears (yea, that could probably get a little messy).

Usagi and the girls are trying to skip out on a training session when they discover Usagi has dipped a toe into Naru and Umino’s love life. After berating her for setting up Naru for an unexpected visit from Umino after school they send her to check on them. Usagi finds them awkwardly doing alright, and parting ways. As she spends a moment drooling over thoughts of Mamoru and disappointed she didn’t catch Naru and Umino flirting NEPHRITE unexpectedly appears on the sidewalk near Naru seemingly in a lot of pain. Which makes a lot of sense, SINCE HE SHOULD BE DEAD ALREADY.

Turns out Nephrite is there to warn Usagi, Mamoru, and the Senshi that Beryl and the four Kings are back, and their goal is to revive the Dark Kingdom, but their real concern is Past Wiseman, who used the Bloody Opal to bring them back from the dead. Nephrite has returned with all of his past memories, and not only of the modern day, but his memories of his time serving under Prince Endymion have begun to trickle back.

In true nature of Sailor Moon, Nephrite is kidnapped by his teammates and brought back to Beryl where he is made to stand at her side again, only suspecting that he simply couldn’t resist seeing Naru again. From the inside he works to help the Senshi win.

When Beryl challenges the Senshi to a rematch the Senshi are sent on a mission to the 4 pillars to destroy the Emerald Gate and the boundary keeping the city trapped. While separated, Sailor Moon and Tuxedo Mask find themselves against Queen Beryl herself. While Tux fights, she concocts a plan to trick Beryl into leading her to Past Wiseman AND IT WORKS! At the same time, Jupiter is battling Nephrite, who reveals Past Wiseman is looking to resurrect Death Phantom.

After an epic Beryl and the Four Kings rematch you’re going to want to watch yourself we learn that Past Wiseman can reincarnate their souls from death in a painful, horrible way. Usagi speaks to Beryl with kindness, requesting that they be friends. She recalls their battle and regrets that she was not powerful enough to reincarnate them at the same time to live normal lives.

Tuxedo Mask makes his epic entrance in an effort to distract Beryl, Jadeite, Zoisite, and Kunzite, and allow the Senshi and Sailor Moon to escape.

Enter Nephrite with the Black Crystal, a Good replica of The Black Crystal which released Past Wiseman. He explains that like the Silver Crystal, the Black Crystal can be used for Good. That the crystal is meant for Tuxedo Mask in the same way the Silver Crystal is meant for Usagi. He calls upon the power of the Black Crystal to awaken the Four Kings memories of how they really came under Beryls control. The Black Crystal appears to Tuxedo Mask as the Kings call on him to defeat Past Wiseman and destroy the Bloody Opal. The Senshi call upon the power of their planets, paired with the help of their paired King, the entire group of 10 destroy Past Wiseman.

With only Queen Beryl left to defeat, Sailor Moon calls for friendship and is met with anger. During her attack though, Beryl collapses and dies in Usagi’s arms, ultimately while admitting she is afraid to like Usagi and forgive her for taking Endymion away from her.

Usagi uses her power to reincarnate Beryl and the Four Kings as regular humans with regular lives on Earth. A far better ending than the original Season 1.

The game ends with Naru teasing Usagi about Umino and owing her for being late again. She threatens to make Usagi split to buy him flowers to make up for it. Usagi closes it out teasing Naru for her feelings. Honestly… the cutest shit ever.