User blog comment:Seieireppa/Nanako’s Magical☆Mystery☆Adventure, part 4/@comment-24799642-20150317032823/@comment-1419424-20150317042245

It cannot be Kota, because I stated in red that Julius' room was a closed room until Kota got the key from Sakaki to open it.

It also cannot be Gilbert or Alisa, because Knox's First Commandment and Van Dine's Tenth Rule both state that the culprit must be someone mentioned in the early part of the story. Were the culprit to be someone not mentioned at all until the final moment, that would be vastly unfair on my part as the author.

Finally, while the howdunnit for your Sakaki theory is plausible, I already stated in red that Julius could not have been killed via direct or indirect means. Discovering the nature of this seemingly impossible crime is your job as the reader. Additionally, since this mystery is directed at those who have played the God Eater games, completely modifying any character's personality for the sake of inventing a motive would be a crime I would never even dream of committing.

(P.S.:  One thing that is common throughout all mysteries, and I mean all, is that the person who first discovers the body is never the culprit, and I don't intend to break tradition here, especially not in my first written work in the mystery genre.)