"Eve: The Lost One" is a direct sequel to Eve Burst Error.
The game tells what happened in Eldia after the young queen became the ruler of the country.

The player takes the roles of the female detective called Kyoko, and the mysterious Snake, as they try to solve a complex mystery full of betrayals and political intrigues.

Kyoko is the more standard protagonist, an agent who investigates a murder case. She is much more talkative; she makes much more comments, meets more people, her thinking is less enigmatic, her motives clear.
On the other hand Snake is much more mysterious. It's not possible to know know his true identity, his goal is unknown, and it's impossible to tell whose side he is on.

[Edited from Mobygames]