Yakumo Yukari is the Youkai Sage who appears when least expected. She modified the Yin-Yang Orbs for long-distance communication during the Underworld incident, so she could send Reimu to go and resolve it. Suika Ibuki is an oni who lives on the surface. She heard about the Underworld incident and the communication device from Yukari and agreed to her plan because it sounded fun. She'd also be able to sit back and relax. That's why she also sent Reimu to go and resolve the incident. Aya Shameimaru was investigating another matter for her newspaper. Her investigation was related to the Underworld incident, but she didn't want to go to the Underworld herself, so, of course, she sent Reimu instead.

While Reimu headed toward the geyser to resolve the Underworld incident, the youkai gathered together at Hakurei Shrine. Suika was in charge of handling the communication with Reimu, but she would occasionally fall asleep. Yukari sat next to her and helped herself to Hakurei Shrine's tea. And Aya wrote in her notebook whenever they received a message from Reimu. "I want to go home and enjoy the hot springs!" It is said that every so often, the regretful cries of Reimu could be heard from the Yin-Yang Orbs, but they echoed unanswered throughout the peaceful shrine living room.

Yukari modified the Yin-Yang Orbs so they could be used as convenient communication devices that allow people to talk with each other over long distances. Yukari explained it to Suika by saying they were like mobile phones with TVs attached... but Suika didn't understand. The modified Yin-Yang Orbs look almost exactly the same as the shintai of Hakurei Shrine handed down through generations of shrine maidens―the same Yin-Yang Orbs that Reimu usually takes with her to resolve incidents. But it is unknown how exactly they are connected.

Suika finally perked up when she heard the message that Reimu had made contact with an oni who lives in the Former Capital. She jumped onto the table and almost broke the Yin-Yang Orb in her excitement at hearing her old friend's voice through the communication device. Yukari almost spilled her tea when she saw Suika might actually break the Yin-Yang Orb, and Aya smiled mischievously because she sensed she was about to hear something that would make for an excellent article. Reimu, who had been sent to the Underworld by those three, engaged in battles of bullets with the oni of the Former Capital and then the Mistress of the Palace of the Earth Spirits... And all the while, she shouted about how she wanted to hurry home and bathe in a hot spring.

"...There. I defeated the cause of the incident." The tired voice of Reimu echoed out of the Yin-Yang Orb, but there was not a single reply. "Heeeey. You're there, aren't you?" Reimu was growing impatient as she continued to call out. However, Suika had already fallen asleep, and Aya was too busy writing her article, so neither of them heard her. "Someone say something already!" Yukari quietly spoke out loud after another one of Reimu's messages... "Hmm, yes, the tea here doesn't taste that great." Only these three youkai know how Reimu reacted when she returned to the surface...