From Scratchpad

In order to start this quest, you must be at least level ten.

Snakeman requests that you head over to the Third Home Camp at X=17 \Y=18 of Suginami. Go there and talk to the guard there. He asks that you kill twenty Cait Siths(ケットシー) and one Manifestation of Destruction Cait Sith(荒ぶる化身ケットシ). The latter is at least five times the size of a regular Cait Sith, so he should be easily identified. In the event that you lose track of your kills, open the Quest menu, click on the Episodes(エピソード) tab, and then double-click on Act Three. You will get an information box that details your quest goals.

Once you are done killing Cait Siths, talk to the guard once more and he will ask that you kill ten Ingumais(イヌガミ) and one Familiar of Chaos Shikigami(混沌の使い魔シキガミ). These devils can be found X=21\Y=17 of the Suginami map. Kill those and return to the guard at the camp. Report to him and you will now have to return to Third Home.

Once you return to Third Home, you will have to go to the warehouse, where you will be thrown into your first boss battle. Prepare yourself, and gather some party members as well. Once you are ready, talk to the guard in front of the shutter door and he will ask if you want to go to the warehouse. He is behind the pharmacy. Say yes and you will be moved to the next area. Move forward until you see another guard and a computer.Talk to the guard and he will hand you a clearance card for the computer. The clearance card here works in the same fashion as dungeon plates.

Once you get to the boss room and finish the movie, you will be confronted with One giant Taaraka and ten shikigamis. The shikigamis have a tendency to gang up on a single target, so it is best that you take the shikigamis out quick. Luckily, they are weak against fire, so use high-power fire spells. Zan also works. Do not use any blunt weapons, thrusting weapons like knives and spears, electricity, rifles, or shotguns. All the attack types that I just listed will either be nullified or reflected back at you.

Once Taaraka is alone, unleash a barrage of ice spells. Since Taaraka's physical attacks are strong, be sure to have a devil or a player act as a medic. Once you are done killing Taaraka, report back to Snakeman, who gives you two thousand makka as payment.