Jacta alea est

Rome, 44 B.C. —
Jitter, a girl of a noble family, visits Julius Caesar.

Caesar and Jitter
©SNEEDLE / no1game.net

Caesar:  "Good morning Jitter, you look so fine"
Jitter:  "You look fine too, Mr. Caesar"
Caesar:  "Well, Jitter, I have something to give you"

cipher and keys

Jitter: "What is it?"
Caesar: "It indicates something I desire"

— What's this thing which Caesar desires?

Answer:

*The original version (Japanese) was made by Nao Fénix.
The story is based on SPQR, a point-and-click game series by SNEEDLE / no1game.net

The answer phrase might look gibberish, but just enter it.

The screenshot was taken from "SPQR Episode 3", which is set in 44 B.C.,
immediately after Caesar was appointed "dictator perpetuo" of Rome.