Ainrand Leslie

Ainrand Leslie (アインランド・レスリー, Ainrando Resurī) is a mysterious entity said to have been an entrepreneur with unusual items. Many rumors revolve around Lesley and it's not known whether the person is human or an undead, or even exists or not.

He is the owner of the infamous and elusive Leslie Camp (レスリーキャンプ, Resurī kyanpu).

Leslie is the one behind the volunteer soldiers amnesia, using a drug made from a relic to erase their memory, and likely also take everything too modern they could have on them.

Level. 13 Heart, Open, A New Door
Team Haruhiro and Kejiman stumble upon the Leslie Camp while on their escort mission, from what Merry says before the camp it's likely that one of the people resurrected before her know Leslie.

In the camp, there according to Kejiman it seems like a number of the rumors surrounding the Camp turn out to be true.

While in the camp they hear Hiyomu voice, who welcomes them in the camp and declares Leslie being her master but the team doesn't recognize her voice.

The interior of the camp seems to confirm some of the rumor on Leslie as the whole camp seems to be a relic and contains a number of other relics and a door to Parano.

Level. 14 Parano-mania
He isn't named but as Hiyomu call him master, the man appearing in the last chapter of Parano-mania likely is Leslie.

He "captures" team Haruhiro, team Io, Alice, and Reon, he chose to release most of them after erasing their memories in a situation similar to the beginning of the series but keeps 2 people for other use.

Quotes

 * "Alright then; I will show you how to use the ring. The price for it, however, will be your new wife."

Trivia

 * Name may be a reference to writer Ayn Rand.