Iroha remembers that her wish was to cure her younger sister, Ui’s, illness; however, there is no sign of Ui’s existence in her life. She goes to Kamihama City to find clues about her, but is attacked by a Witch and subsequently saved by a trio of Magical Girls, Momoko, Rena, and Kaede. There is a rumor going around about the Friendship Ending Staircase at Rena and Kaede’s school. Momoko and the others believe that a Witch is involved in the rumor, so they’ve been investigating it, but…

Iroha decides to investigate Kamiahama City’s rumors in order to find clues about her missing sister, Ui. Mitama introduces Iroha to Tsuruno, the daughter of the owner of a Chinese restaurant called Banbanzai. Tsuruno asks someone who is familiar with the rumors to help investigate, but Yachiyo is the one who shows up at the meeting spot. Tsuruno says Yachiyo is knowledgeable about the rumors of Kamihama City. The three suspect that the Séance Shrine may have something to do with Ui’s disappearance…

At the Séance Shrine, Iroha wrote her sister's name, Ui, and Yachiyo wrote the name of her former best friend, Mifuyu, on votive plaques. As if to confirm the truth of the rumor, Ui and Mifuyu appear, but they are twisted imposters of their loved ones. Iroha and Yachiyo are attacked by the fake Mifuyu and the master of the Séance Shrine, a Horse Monster, and find themselves in a bind that threatens to end their lives. Iroha's Soul Gem gets cloudy, making her slowly lose consciousness. What sort of transformation will she undergo?

Iroha moves into Mikazuki Villa and transfers to Kamihama City University Affiliated School. She discovers that even though Kaede goes to the same school, she is unable to contact her. Iroha has a hard time getting used to her new surroundings, so when she sees that Rena doesn't have many friends in class, they decide to eat lunch together on the rooftop. Iroha is still gathering information about various rumors, and Rena tells her about the rumor of the Invisible Girl and Endless Solitude. Tsuruno hears about the rumor of the Radio Wave Girl from a regular at Banbanzai and tells Iroha about it.

Iroha hears about Nemu Hiiragi, the best friend of Iroha’s younger sister, Ui, from Kuroe. Iroha finds out that Nemu, who is also a member of the Magius, remembers her and asks Kuroe to take her to Nemu so they can talk. Iroha, Yachiyo, and Kuroe head to Hotel Fendt Hope, the headquarters of the Magius. When the trio arrive at Hotel Fendt Hope, they have an encounter with the Amane sisters. While Yachiyo distracts the Amane sisters, Iroha and Kuroe make their way into Hotel Fendt Hope to find Nemu, but they bump into Rena Minami and Kaede Akino, who are dressed as the Black Feathers.

Iroha embarks on a journey to find her friends from Mikazuki Villa. Kuroe is genuinely concerned about Iroha so she decides to tag along. Meanwhile, Felicia and Sana are working inside of the Magius as Black Feathers. Felicia proclaims that she will not return to Mikazuki Villa until she finds out how they can avoid becoming witches. Sana begins to question the actions of the Magius while she manages the people captured by the Uwasa,. Mifuyu, who is acting as a White Feather, finds herself in a predicament when she reunites with an unexpected person. Amidst the intricate tangle of everyone’s emotions, Touka announces her strategy to save all Magical Girls. What could it be?

Kuroe lets Iroha get ahead of her while fighting with Magius. Kuroe hears a whisper that puts her in a shock: “Did you forget about me?” At the same time, Iroha is hearing Ui’s voice. Felicia and Sana are confused about Magius’ plan. Sana has questions and explains her intent to Mifuyu, who seems to have given up on everything. Due to the plan, Yachiyo is after Iroha in Kamihama City, which is filled with a large number of Witches. While there, Yachiyo comes across a Magical Girl from Mitakihara City.

The Magical Girls break into the headquarters of the Magius. After Iroha and Yachiyo reunite, they meet up with Madoka and the other girls, but are confronted by Tsuruno Yui and Mami Tomoe who have become soldiers of the Magius. Mami and Tsuruno, who are being manipulated by another entity, begin attacking the Magical Girls. Iroha and Madoka are in a bind as they are unable to fight back. As a tactic, the Magius summon countless Witches to gather in Kamihama City. The largest ever Supercell is approaching and will hit Kamihama City in six hours. The true identity of the Supercell is actually Walpurgisnacht, the most sinister and evil Witch ever.

Tsuruno, who had merged with the Uwasa, is defeated, which triggers Touka from the Magius to direct her rage toward Iroha and her friends. Touka sends the Uwasa of the Soldier Bear army to attack them. Nemu is upset with Touka’s actions and at how things aren’t turning out the way she intended. Meanwhile, Iroha finds herself alone in a strange world. She is sitting in a seat in a theater where a Magical Girl named Mel is predicting the future. When Iroha sees Mel, she remembers the past events that Touka showed her at the Memory Museum.