Mi’ihen Highroad
Save your game at a 
Save Sphere before you start the next section, because a timed event will kick off as soon as you enter the Mi’ihen Highroad. You must enter it by transporting down from Celsius or by entering from Luca, not from Mushroom Rock Road; otherwise, you run the risk of altering the results of the Mi’ihen Highroad Mystery quest later on in the game (you don’t need to read up on this yet).
Helpful Hint
This next Mission is a race that will have you trekking all the way across the Mi’ihen Highroad again. You may want to remove the element of random encounters by equipping one of your characters with a 
Charm Bangle to get the 
No Encounters Auto-Ability, which makes this next Mission much easier.
Mission: Machina Mayhem!
You’ll compete against an invisible group of Al Bhed who are also working to dismantle/destroy the Machina in this area. The race will automatically end once the total between the two teams reaches 13.
Follow the Mi’ihen Highroad and look for green square icons 
on the mini-map. Use these to identify where the different Machina groups are located. You can find 13 teams of Machina, but they will slowly disappear as the Al Bhed dismantle them.
This Mission is basically a timed event. The Al Bhed team will dismantle a group of Machina every 40 seconds while you’re out on the main map wandering around (not during battles or while the menu screen is open). This means you have 4 minutes and 40 seconds to defeat 7 groups of Machina, which shouldn’t be a problem if you’re quick.
You’ll need to go out of your way to find a few Machina. One of them is accosting a citizen in the center rock on the path just north of Rin’s Travel Agency.
Helpful Hint
If you’re using the 
Dark Knight Dressphere, consider having them learn their “Proof” abilities. This includes Poisonproof, Stoneproof, Confuseproof, Curseproof, and Deathproof. Dark Knights already have strong attacks, but these defensive abilities are automatically applied and can make Dark Knight particularly effective during boss battles for bosses that apply negative status effects.
When you go down the Newroad North, there’s a citizen and a Machina up on the top of the cliff. If you get close enough to them, Yuna will automatically jump up to rescue them.
Just a little bit further than that, on the right side of the map, is another Machina that you can drop down to as long as the Al Bhed didn’t beat you to it. Just hold the 
button as you approach the cliff to drop down.
Helpful Hint
If you were able to trigger this sequence, you’ll see a cutscene of Rikku dropping down first (shown in the screenshot below).
You can park this for now, but it becomes relevant during the CommSphere sequence in Chapter 4. You don’t need to trigger it, but you can speed things up later if you did.
Your reward for completing this Mission successfully and beating the Al Bhed is 10,000 Gil and an 
Undying Storm Garment Grid. This will automatically conclude the Mission and send you back up to the Celsius, but before you leave, go back down and complete the Publicity and Marriage Campaigns and pick up the treasure chests if you’re feeling adventurous:
Side Quests
A list of the NPCs that you can speak with to earn Open Air / Argent Publicity points and Marriage matchmaking points along the Mi’ihen Highroad during Chapter 3.
Mi’ihen Highroad - Oldroad South End
 1 |  Phoenix Down ×4 |
| 2 | 2,000 Gil |
| 3 |  Hypno Crown |
Mi’ihen Highroad - Newroad
Your next destination is Mushroom Rock Road.
Checking the “Mi’ihen Highroad Complete” box adds the Story Completion Percent for the automatic scenes in Mi’ihen Highroad.