Ouji Kousaka
About
Due to having blogged many times on his cellphone, which is connected to the Eighth's diary, he becomes a "Diary Holder Apprentice". His diary helps him save his friends, but it only reveals his successes, not his failures, which makes Yuno able to shoot him with a crossbow. Since he is inadvertently working as the Eighth's spy, Yukki destroys his diary in chapter twenty-seven, though does not die because it was not a true future diary.
(Source: Wikipedia)