Spring, a Date, and Playing a Little Sister

Spring, a Date, and Playing a Little Sister (春とデートと妹ごっこ) is a Drama CD released on January 6, 2012. The story takes place between the events of Pentagon++ and Nise Random. This Drama CD marks the debut of Uwa Chihiro and Enjouji Shino's voice actors.

Summary
One day, the five original members of the Student Cultural Society find a mysterious note. On the note, they see the scribbled names of the five second years and a message: "You must grant the wishes of Uwa Chihiro and Enjouji Shino, otherwise bad things will happen." Believing it to be the work of No.2, the friends decide to obey the bizarre note. Asking their underclassmen what they can do for them, the Pentagon endeavor to do their best to grant any wishes Shino and Chihiro may have.

Synopsis
On an otherwise normal day, the five original members, or "Pentagon", of the Student Cultural Society come across a bizarre note. On the note are the names of the five second years, a few stars, and a message saying "You must grant the wishes of Uwa Chihiro and Enjouji Shino otherwise bad things will happen." The Pentagon suspect that No.2 is behind the note since a similar message preceded the Time Regression phenomenon.

Shino and Chihiro soon enter the clubroom, surprising and startling the second years. Inaba calls all the second years to the hallway for a private meeting. At that time, they remember Shino having mentioned something about wanting to eat parfait. Just as Aoki denies that could be a wish, he suffers a stomachache and rushes to the restroom. The remaining members realize that getting sick could be a consequence for disobeying and, considering No.2's past actions, the friends decide to grant the wishes of Chihiro and Shino.

The seconds years offer to treat Shino and Chihiro to parfaits and Aoki suddenly returns, his stomachache gone. Knowing that this cannot be a coincidence, the Pentagon invite Chihiro and Shino for parfaits at a family restaurant while keeping the content of their conversation a secret. At the family restaurant, the StuCS enjoyed parfaits together and fooled around a bit with Aoki asking Yui to feed him. Yui ends up tricking Aoki and ate the entire parfait quickly. Shino then mentions how feeding each other seems like a thing couples would do and, after some unnecessary comments from Nagase, Shino becomes curious of what Taichi and Inaba's dates are like. Knowing they must grant any wish, Taichi and Inaba decide to go on a date and let Shino and Chihiro follow to observe.

During the Golden Week holiday, the StuCS meet up. Taichi and Inaba are uneasy and embarrassed about letting others watch their date, but seeing no other choice, they decide to do it for the sake of the StuCS's peace. Taichi and Inaba quickly have a brief argument on where to go first, either the Electronics shopping area or Pro-wrestling match first. They end up going to the Electronics shopping area first, Taichi stating, "Inaba is important to me, so I'll go wherever Inaba wants to first." Inaba reacts cutely and Nagase labels this side of Inaba, "Dereban". While they are in the shopping district, suggestions by Nagase, Yui, and Aoki make Shino want to see Taichi and Inaba hold hands. The two proceed to hold hands but are embarrassed about it.

Later, the gang passes a cosplay shop which is holding a contest to dress up as a character and the winner will receive ￥15000. Shino insists that Nagase should enter the contest and Inaba teases Nagase, reminding her that she can't refuse. Nagase obeys and dresses up as a Mahou-shoujo (magical girl). The friends later go to a parfait shop where Shino wants to see Inaba feed Taichi a parfait. Embarrassed and a bit angry at the others who keep giving Shino suggestions, Inaba went on with feeding Taichi. Unfortunately, she was very violent with her feeding and missed Taichi's mouth and hit him in the face, knocking him over. Inaba started crying and thought Taichi was going to die, but luckily it was just an overreaction on Inaba's part.

At sunset, the group went on to watch Taichi's Pro-wrestling match. The opening act invited an audience member to fight a "stupid wrestler" for entertainment. Shino and Chihiro wanted to see Yui being cool, so Yui, having no choice, entered the ring and performed some karate moves. Shino admired Yui's strength as a girl and the second years whispered about Yui finally overcoming her Androphobia.

After finishing the show, the group coincidentally encounter Fujishima on her jog. Fujishima, still a bit depressed about having lost the election for class representative, noticed that Taichi is always surrounded with girls and getting along with them well. She then remembered Watase's observation that Taichi might have a harem, which made Shino and Chihiro interested to see what it would be like if Taichi went on a date with Yui and Nagase. Aoki and Inaba were shocked but, knowing that this is a phenomenon, they had no choice but to give their approval.

The group got together again the next day to watch Yui and Taichi have their date first, and Taichi noticed that Yui was wearing something different than usual. The two of them only walked around and talked, but Inaba and Aoki followed closely behind, clearly enraged. The gang eventually encounter Gotou and Fujishima again, and the two confirm that Taichi does indeed have a harem. Gotou leaves in envy and anger, but not before telling Taichi that he'll take off 30 points off his test, and the group continue their way home. Along the way, Nagase asks Shino why she likes Taichi's voice, which inspires another wish from Shino. She wishes for someone with Taichi's voice to confess to her. Being the only person who could possibly have Taichi's voice, Taichi has no choice but to think of a way to confess to Shino or suffer the phenomenon, all the while Inaba becomes more and more angry.

The next day, Taichi calls Shino to a shrine near the school, claiming there is something important he must talk with her about. Meeting him at the shine, Shino nervously waits for Taichi to speak. Taichi confesses to Shino saying, "I love you, be my little sister." Shino shocked and extremely happy, was speechless and then started stumbling over her own words. Later that day, Shino called Aoki for advice, only to be told to "go for it" from Aoki. The next day, Taichi and Shino meet for a date. Taichi tells Shino that she doesn't need to use polite language and to call him "onii-chan". Shino calls Taichi "onii-chan", but was a bit embarrassed about it. Taichi himself became extremely happy and collapsed before muttering, "My own little sister is Number One in the world, but you can be Number Two."

After too much embarrassment, they decided to refer to each other normally. The two went on with their date, but Shino noticed that a group of suspicious people wearing sunglasses and masks were following them. One of the suspicious people went right up to Shino, clearly displaying animosity, but the others apologized and dragged that person away before anything happened. Shino noticed that their voice was really familiar. The suspicious people are revealed to be the rest of the StuCS, who gathered to spy on the date without Taichi or Shino knowing. Inaba, who could not stand Taichi being with Shino, overreacted but was stopped by the rest.

With their date concluded, the two left for home separately. Taichi, instead of going home, first went straight to the group of people who had been following them the whole time, and Shino identified them as the second years of the StuCS. Confused about whether their date was a joke or serious, she went home.

After school the next day, Shino and Chihiro are alone in the clubroom when they hear some ruckus outside, obviously the second years. Shino wanted to go check it out out but was stopped by Chihiro, who suspects that something was up with the second years, realizing that they were granting their every request. To test it, Chihiro made a request that made Inaba angry, causing her to rush in, leading to a huge argument amongst the club. Shino, having had enough, shouted angrily and demanded to know why the second years were acting the way they did. Taichi and the others, knowing that they can't mention Heartseed, only told them that they wanted to make them happy. Shino remembered the note she wrote and asked them if they mistook that paper for a command. Shino then explained that it was just a piece of paper with a spell written on it that she learned about from a book.

With everything cleared up, the StuCS resumed their normal activities. Later that day, as Chihiro was returning home, he realizes that the second years' actions were driven by Heartseed. Two weeks prior, Chihiro was approached by Heartseed and asked if he wanted power. Heartseed told him that he only had to do one thing successfully and that power would be his to keep...

Cast

 * Mizushima, Takahiro as Yaegashi Taichi
 * Toyosaki, Aki as Nagase Iori
 * Sawashiro, Miyuki as Inaba Himeko
 * Kanemoto, Hisako as  Kiriyama Yui
 * Terashima, Takuma as Aoki Yoshifumi
 * Tōyama, Nao as Enjouji Shino
 * Toyonaga, Toshiyuki as Uwa Chihiro

Trivia

 * This Drama CD explains how Chihiro got the power of Illusion Projection from Heartseed.