Second Security & Dimension Trouble

 is the twentieth chapter of Trinity Seven manga series, released on August 9, 2012, in Monthly Dragon Age September 2012 issue and later compiled in the fifth volume on January 7, 2013.

Summary
As the school broadcasts an announcement for Arata to the Headmaster's office immediately, the boy, along with Sora, rushes along the hall while lamenting that he would not be able to enjoy his lunch. Sora suggests that the Headmaster may have something to give him, although Arata notes that if that was the case, there would no reason for him to come to the office so urgently. Unfortunately, due to the distraction, he does not see a girl coming around a corner and accidentally bumps into her. As Arata regains his senses, he finds himself in front of Mira who's underwear has been unintentionally exposed. Despite the situation, Arata comments to an increasing embarrassed Mira that she is not wearing any bunnies, causing her to beat him up quite viciously.

In the Headmaster's office, Master Biblia laughs while commenting on Arata's luckiness in front of Mira, Akio, Lilith, Sora and an injured Arata. Arata remarks that he did not intentionally look, although Sora still notes that he was glad regardless, to which he confirms, much to Lilith and Mira's chagrin. Mira then asks the Headmaster for the reason why he called them to his office. He reveals that he is suggesting Arata temporarily become the second seat of Grimoire Security. While Akio seems interested, Mira is strongly against the idea, refusing to work with the Demon Lord Candidate. Nevertheless, the Headmaster states that Arata has already accomplished resolving several high level incidents. Lilith recalls that he has helped prevented Arin's Ira, Yui's Avaritia, and Lieselotte's Acedia Breadown Phenomenons. Mira continues to object, although Lilith also affirms that she too is against the decision. Arata then inquiries the job details of an Inspector; Akio replies that simply they fight against evil magi. Arata enjoys the idea of being a hero, while Sora notes that with his stripping magic, he can render anyone defenseless. Although, Akio also jests that he would not enjoy the situation if he was against a male magus, much to Mira's uneasiness. The Headmaster tries to appease the atmosphere by also mentioning that he will have Lilith join them as well, although he is concerned with sending just Mira and Akio for this mission as well. Answering Mira's puzzlement, Master Biblia reveals that they will be traveling to a location that was recently destroyed, one of the "Three Great Magical Academies", the Royal Libel Academy.

Later, in his room, Arata contemplates on how to prepare himself on his bed until Sora moves on top of him. He asks her if she will return to her grimoire form, but Sora insists that she looks better in her current form, to which he has no problem. However, Mira and Akio unexpectedly enters the room only to discover Sora straddling her master. While Mira is embarrassed at the sight, the duo tells an unfazed Akio that they were discussing the upcoming mission. After settling down, the four attempt to converse, however due to the prior scene the atmosphere is awkward. Mira embarrassedly blames Arata for shamelessly interacting with Sora, although he insists they were not being serious despite admitting he enjoyed the experience right afterwards much to Mira's dicomfiture. Next, Arata assumes the reason the two are in his room is to provide information on the mission which Akio verifies. Although, Akio also reveals that she had to come along because Mira was too uneasy to enter a boy's room by herself, as well as change her underwear due to Arata seeing them. After Mira punishes him, Arata inquiries about the Royal Libel Academy. The girls explain that Libel is another magic academy on the same level as Biblia, however during Lieselotte's onslaught, the academy was destroyed. Sora notes that she had also sensed a great magical pwer appear then disappear around the same location as well. Furthermore, she also states that the feeling was similar to when Hijiri vanished. Akio continues to explain that along with Libel Academy, the surrounding towns were also destroyed, resulting in the loss of over a thousand lives. Although Arata may have stopped the Breakdown Phenomenons easily, they are still nevertheless quite dangerous. Mira discloses that the group will be heading to the site of the ruined Libel Academy the next day to investigate and eliminate the culprit if discovered. Sora questions the method of transportation that will be used and Mira explains that they will be using a magic warp device to teleport to the location, much to Arata's excitement. With the end of their conversation, Sora then proceeds to tease Mira using the fact that she entered a boy's room with her pajamas. The two, along with Akio, continues to embarrass Mira until Sora reveals that a bug is next to Mira. Startled and frightened, she accidentally runs into Arata onto the floor. Due to the noise, Lilith barges into the room to advise him to sleep for the mission, only to stumble across the scene of Mira riding on top of an unconscious Arata. Lilith abashedly tells a likewise embarrassed Mira to enjoy themselves while the leader of Grimoire Security tries to explain the situation.

On the next day, the Headmaster is amused upon seeing the girls and an injured Arata. After confirming that they are preparing, he begins starting the teleportation device until the device suddenly starts malfunctioning. Determining that someone is interfering with the transfer, the group has no choice but to trust the Headmaster since stopping could result in disastrious results. As the device begins to crumble, one of the girls grabs Arata's hand before the machine eventually breaks.

Arata then suddenly finds himself with only Mira in front of an unknown building. Sora notes that they seem to have arrived safely, although she senses that the atmosphere resembles her World Reconstruction ability. After an unconscious Mira awakens, she recognizes their location as the Royal Libel Academy despite the school supposedly being destroyed. Unexpectedly, they are approached by a girl who Arata recognizes as Hijiri.

Characters

 * Arata Kasuga
 * Sora
 * Mira Yamana
 * Master Biblia
 * Akio Fudo
 * Lilith Asami
 * Ilia as Hijiri Kasuga

Trivia

 * Arata and Akio comment that Mira changed her underwear after becoming conscious of Arata. This is a reference to the event in Macro Spell & Exciting where Arata accidentally caught sight of Mira's underwear after Levi's spell exposed her skirt.
 * Master Biblia states that Arata will temporarily be the Second Seat of Grimoire Security. Lieselotte originally had this position until she performed a taboo experiment and disappeared into the Eternal Library.
 * In response to Mira's objections to Arata joining Grimoire Security, Lilith recounts several of Arata's past achievements in resolving the following incidents:
 * Arin's Ira Breakdown Phenomenon in Grimoire Security & Abort
 * Yui's Avaritia Breakdown Phenomenon in Labryinth & Ninja
 * Lieselotte's Acedia Breakdown Phenomon in Special Training & Big Event
 * Master Biblia sends Mira, Akio, Arata and Lilith on a mission to investigate the destruction of the Royal Libel Academy during Lieselotte's onslaught on Biblia which occurred in Special Training & Big Event.
 * The annihalation of Libel was first mentioned in Last Crest & Problem Solving
 * Sora recalls sensing a large magical power appear then disappear in Libel's general location, noting that the feeling was very similar to Hijiri's vanishment. Sora is referring to the incident where a Breakdown Phenomenon occurred in Arata and Hijiri's hometown, which eventually resulted in causing Hijiri to disappear.