Luckily for Eren, the man in the office, who was most likely the Shadow Essence and the "boss" mentioned earlier, was asleep, probably from too much alcohol as there happened to be wine bottles on his desk. For a split second, the soul link that Eren had started to show him some kind of mental image, showing that there was a darkness coming out of this man, definitely confirming that this was the Shadow Essence that Eren and Kaika were supposed to destroy.
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Soon, Takahisa finally woke up groggily, worn out from whatever he did to completely seal Ayimu. ".....Armin...." Takahisa mumbled as his vision was still blurry, but could barely make out that Armin was there next to him.