Before your fifth time travel, you must pass Nex's test again. I know I keep saying this, but trust me, Nex will be even stronger this time around!

When you defeat Nex, the Time Gate to the year 2230 will open.

You won't be authorized to travel time until you defeat Nex the Gatekeeper of Time.

Ah, you've passed Nex's fifth test. Now then, you should be able to access the Time Gate to the year 2230.

Take the Time Traveler's Pocket Watch and go through the Time Gate.

Come back after you've passed Nex's test. Nex the Gatekeeper of Time lives inside the Old Tree of Tera.