Investigation on the Seabed

*Investigation on the Seabed* is the fourth campaign mission of Spriggan: Lunar Verse. There has been a discovery that an intruder has infiltrated the ruins managed by ARCAM. Tatsuki must investigate the ruins to determine the intruder's identity and objective.

## Briefing

Graham informs Tatsuki of an information being leaked that an intruder's presence is discovered inside the ruins managed by ARCAM. He states that according to the materials, the site's investigation has been completed once, and the investigation before the blockade is currently in progress. The intruder's objective remains unknown, so Graham instructs Tatsuki to head to the ruins and locate them.

## Mission Overview

Tatsuki is already inside the ruins before he receives a call from Graham, telling him about his lack of knowledge on the intruder's location and to remain cautious. As Tatsuki explores the ruins, he discovers that it is infested with ancient creatures that took no pleasure with intruders raiding the ruins. Fighting against his enemies, Tatsuki eventually comes across a diver suit in one of the areas that hints the intruder's presence. Then, he searches a small room close to his vicinity, although it only contains a moon-like pattern on the floor.

Confused on how to proceed next, Tatsuki returns to the room where he founds the diver suit, only to witness the legendary Spriggan, Yu Ominae, examining the suit. As he approaches Yu from behind, however, Jean fires rounds at him, advising Yu to not be out of focus. He then briefly jokes about how Yu would be dead numerous times without him. Jean would then recognizes Tatsuki from the operation involving the U.S Army invading the quarry ruins. Yu makes a comeback stating to Tatsuki that Jean is senseless, much to the latter's annoyance from that comment. He informs Tatsuki to stay vigilant that there could be a mole within ARCAM, before apologizing for interrupting his mission progress. He then decides to exit the room with Jean, but not without giving Tatsuki a crescent-shaped lithograph since they could not determine its usage purposes.

Tatsuki then experimented with the lithograph's function by using it while standing on the glowing, circular-shaped pattern in the same small room, which results in him being teleported to another room. There, he spots new adversaries waiting to challenge him. He breaks the iceberg that appears to contains a key to operate the floodgates that spread throughout the ruins. He heads to another room where he discovers there is another pattern similar to the one from the small room, although it has been submerged by excessive amount of water, and Tatsuki cannot reach it since he cannot swim. He can choose to reach another room where the sluice pedestal is located to drain the water submerging the glowing pattern by jumping on the small platforms leading to it, or taking a safer method by heading to the left hallway where he must activate switches to unlock the gates, dodge spike traps, and eventually dropping to the room's entrance from above. Either way, he arrives to the room and utilizes the key he obtained from the iceberg earlier to drain the water. Afterwards, he heads to the circular pattern and uses the lithograph to transport to another place.

Upon arrival, Tatsuki witnesses a woman, who appears to be an intruder, knocking on the door in a futile attempt to open it, much to her frustration in unable to do so. Eventually, she notices Tatsuki and concedes with the fact that he serves as a jam for the locked door. A battle between them begins, and the woman appears to be a dangerous adversary with her high acrobatics maneuvers and attacks, but Tatsuki manages to secure a victory of this duel by beating the woman unconscious. The door seems to contain a gap that has a shape of a crescent. For the door to be opened, Tatsuki places the crescent-shaped lithograph on the missing piece.

Tatsuki slowly walks to the next room where he is greeted upon by a guardian, who only provided a single statement that he only fulfill his main mission by protecting the ruins. It attacks Tatsuki as an intruder. Despite being a difficult opponent to deal against with its powerful defense, strength, and beam attacks, Tatsuki manages to destroy it. The guardian then gives a speech mentioning it is finally released from its long-term duty, and warns Tatsuki that he should never follow the same path as them. An object that appears to be similar to a stone is then released from the cup-like object, and slowly hovers to Tatsuki who then recovers it. Afterwards, a mysterious girl appears out of nowhere, standing right before the object holding a stone-like object.

## Debriefing

Graham criticizes Tatsuki for not following the mission order of discovering the identity and purpose of the intruder before placing her in an unconscious state. He advises him to judge the situation more and act accordingly before switching the topic that the object Tatsuki collected back in the ruins will be left for analysis. He then provides an update on a new AM suit development, in which it is finally completed. The suit is in a prototype stage, where Graham mentions that Tatsuki could finally wear one in future missions, and ARCAM desires to collect data from it in actual battles. However, he then states the negative of wearing the suit, in which Orichalcum is compatible with it and controls it. It requires the user to have a strong mental power to control the suit, otherwise it is useless. He gives an advice towards Tatsuki to read the details from the manual that describes the functionality of the three types of new AM suits before concluding the debriefing.