Shiokishi (潮岸) is one of the 12 Directors of Academy City, in charge of all military aspects such as defense and R&D of military technology. He always wear a HsPS-15 Suit, not because he is paranoid about attacks on him but he can't be at ease without it.
Background
Not much is known about Shiokishi's history other than eventually becoming a director and being involved with much of Academy City's Dark Side. He frequently clashes with Oyafune Monaka to the point where he hates her so much to threaten her daughter, Oyafune Suama, to silence her actions. He is in charge of the military affairs in Academy City and underneath the powered armor, he is an old man wearing a tuxedo outfit.
Personality
He is by far the most eccentric of people, he has invested heavily in his own protection as he considers "safety" a luxury and a key to make to him think more clearly. He is so paranoid and neurotic that: he is always in a powered, created a stronghold to hold off espers or nukes, and has two bodyguard factions that are set to kill each other under circumstances.
Chronology
In the Light Novels he first appeared in Volume 19, he first appears to GROUP in their RV via live feed to direct them in finishing off the survivors of the Spark Signal incident. During the conversation between the two, Tsuchimikado Motoharu comments that Shiokishi's appearance is quite rare instead of using the "voice on the phone," this could be interpreted that it is Shiokishi is the handler of GROUP or at the very least partnered to the "voice on the phone."
Following after the GROUP's mission he becomes an antagonist plotting and attacking GROUP. He is countered by the efforts of GROUP and Monaka. After his defeat he revealed DRAGON's identity, saying it's something he wished he never knew of its existence, but as the one in charge of defending Academy City against the 'outside' he needed to know. Shiokishi was then knocked out by DRAGON afterwards, and it is unknown whether he is dead or alive after that.