Passwords
In order to utilize the more powerful capabilities of the moon base, each of the seven scientists must be in unanimous agreement that this course of action is the correct one. In order to enforce this, each scientist has a password, all of which must be entered at the time when these capabilities are being activated. During their time on the moon base, the seven scientists changed their passwords three times.
After the Homeworld was destroyed, Shion wanted to go down to Earth to live out the rest of his life, and in order to do this, all password were needed. Not everyone was in agreement with him about it, and he ended up pushing the matter too far while harassing Shusuran for her password, which is how he ended up getting thrown in the anti-Sarches brig.
On Earth after the reincarnation, Shion again needed all seven passwords in order to enact his plan of global domination, hoping to use the moon base's amplification capabilities to spread Mokuren's song of death all over the world. Rin, however, needed all seven passwords to activate the moon base's self-destruct function. The two consciousnesses within Rin decided to compromise by simply collecting the passwords for the time being. It is only after all the passwords are collected that we see who wins this struggle of will.
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