[his eyes flash with annoyance. now is not the time to get pedantic with him, Fuu, not when he isn't well.]

The only guardian guarding "time", so to speak--[besides his other self and Braxiatel, but fortunately for them, they haven't got a base spoken of in the riddle, so it isn't them]--is that statue of Poseidon forming that sundial, and since he's the god of the sea, it stands to reason he's the guardian of it as well.

[he sighs and takes another sip of his water to cool off--literally and figuratively] It's a possibility.