Sixteenth Basket of Mantaos

Imagine being forced to live, after death, as incorporeal bodies trapped in a vast space of nothingness for thousands of years, with nothing to do but exchanging past memories with other cohabitants (read: weirdos).  Everybody wanted out, but there was no way to leave the Void... 
Until one day, a young man was finally summoned, as a powerful but reluctant mentor, by a bubbly and motivated but completely naive young girl. Baiyi, finally out of the Void, was the only one who could save all of the other 32 souls from their prison and his summoner might just be The Key to their freedom.
However, Baiyi had to use the techniques and abilities the other souls had taught him throughout the years, and together with his own extensive knowledge of anime and game tropes from his shady and dangerous past as an otaku, to face the biggest challenge of them all: training the clumsy young girl he was forced to partner up with… into a competent sorcerer!

EndlessFantasy Translation 

Why Did You Summon Me？

After seeing the first man spilling the beans, the other two’s jaws loosened too. They blurted out everything they thought Baiyi wanted to hear. How they were introduced into the sect through an anonymous man, as well as the benefits of being a low-rank member of the sect, and then lastly, how they were trained into half-baked 'Shadow assassins'.

Only the last man was still stubbornly tight-lipped. His eyes reflected pupils that were dilated by both fear and rage as he glared at Baiyi. Seeing his companions confessing, he shrieked in fury, "You fucking traitors! Master Butler won’t let any of you go! Not even your family!"

The last cry seemed to have pierced through their minds, forcing them to remember what was at stake. Baiyi was about to ask them about the purpose of their assassination but the resulting fear had crushed any last semblance of cooperation.

The captives were completely paralyzed by the name of the Butler guy.

His Fifth Surprise