1. Mizuki (Konoha Village): Mizuki once helped Naruto learn the "Multiple Shadow Clone Technique", but he later became Orochimaru's experiment and eventually disappeared.

2. Kosuke (Konoha Village): Kosuke is a powerful genin, but he blames himself and is unwilling to upgrade to a jounin. In the end, he disappeared after having a chance encounter with Naruto.

3. Yellow Earth (Konoha Village): During the Fourth Ninja War, Yellow Earth was one of the captains, but later disappeared, and it is unknown whether he died.

4. Hidan (Shikamaru Village): Hidan sacrificed his head in the battle with Shikamaru, but his special body makes his death a mystery.

5. Ibiki (Konoha Village): Ibiki was abused during the battle with Pain and was even killed by Pain, but was later resurrected by Nagato. However, he also disappeared later.