In MIO: Memories in Orbit, at least initially, it’s a little hard to get your bearings. Mainly because the only way to access the map is by talking to Shii directly.
This is because the Nexus hasn’t been repaired and the world is still unconnected. Which, in a Metroidvania, is a bit of an issue, as interconnectivity is everything.
However, it’s not actually that tough to get the Nexus up and running again. In fact, you can do it even quicker if you suck at the game.

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How To Repair The Nexus in MIO: Memories In Orbit

In short, there are two ways to go about repairing the Nexus. One involves being good at the game and proactively filling the pond with Nacre. Then, on the flip side, the other method involves you dying, a lot.
To repair the Nexus, you need to collect Nacre, which is the basic currency of this game. This is earned through exploring and fighting enemies. I wasn’t able to discern exactly how many you need to fill the pond with to repair the Nexus, but it felt somewhere close to 500 Nacre.
You can talk to Shii at the Nexus, and offer your Nacre. Or alternatively, when you die, your lost Nacre will automatically be donated to the pond. When you have donated enough, Shii will then activate the Nexus.
My suggestion would be to gather Nacre to buy all the available mods and upgrades from Mel in the workshop first. Then, if you still need to activate the Nexus, you can gather this extra Nacre for Shii, as there is little other use for it at this stage.
Why Activate The Nexus?

In fairness, you will die several times in this game, so you’ll end up activating the Nexus naturally at some point. But it is best to do it as quickly as you can. Mainly because when you do, you can access the in-game map wherever you are in the world, making navigation much easier.
Plus, you gain the ability to float around the pond on Shii’s tendrils, which seems like a gimmick. But, if you float up to the top right, you’ll find a Coating Component, which will go some way to helping you upgrade your health.

