Capture HQ or Rout
4 Medium Tanks
20 (6 Orange Star, 12 Yellow Comet, 2 Neutral)
3 (3 Orange Star, 0 Yellow Comet, 0 Neutral)
Continuing the trend that started last mission, your best offense is going to be a good defense. And it's going to have to be a very good defense because you have to hold two bridges against a vastly superior Yellow Comet force.
This strategy is known as Fortify and Contain, because if Kanbei's forces break through the bridges you'll be routed easily!
On your end of things, there was an error that prevented preparations from being completed. However, you have 3 Bases to use for deployment. Use them wisely and you'll be fine.
Capture the enemy HQ or Rout all Yellow Comet forces to defeat Kanbei! Clear this mission in 10 Days for alternate ending text and to fulfill one of the three requirements for unlocking three additional missions that begin right after completing the next one, provided you cleared Kanbei Arrives! in eight days or less!
This is one of the hardest missions of Advance Wars' Campaign mode, so this is going to be pretty detailed.
The majority of Kanbei's Units will rush the East Bridge, while only a couple of Units will rush the South Bridge.
If you get through here you'll have something not as demanding to deal with for your next mission.
 Andy & Sami Day 1
On Day 1, move your Medium Tank onto the East Bridge, and if you chose Andy or Sami, you'll be able to use your East Rockets to fire on his Rockets. Use your West Rockets to fire on the Artillery that is in range, but don't move anything else in that area. Move your Infantry 2 spaces East and One space North so it'll be in range to capture a Neutral City on the next turn. Deploy nothing on this turn.
Your Tank will be fired upon by his Tank, but that's fine because it'll get repaired on the next turn. Here they come, with his damaged Rockets Unit on the retreat.
 Andy & Sami Day 2
Have your Infantry begin capturing one of the two Neutral Cities here. Use your West Rockets to attack that Artillery unit, destroying it, and use your Tank to fire on his Tank in the South.
If Kanbei didn't retreat his Rockets Unit it'll be in position to be finished off, otherwise open fire on one of his Medium Tanks.
Here you have a couple different deployment options. You have enough to deploy two Artillery Units of your own or a Rockets Unit to provide more firepower on the Eastern Front, but not quite enough to deploy a second Medium Tank.
 Andy & Sami Day 3 and onward
Finish the capture of the Neutral City, and start capturing the other Neutral City on Day 4 to claim it on Day 5.
Move the Rockets that you deployed into position behind the Medium Tank on the Eastern Front, or if you deployed two Artillery move one Artillery next to the Tank on the Western Front and the other Artillery behind the Medium Tank. Start spreading the damage around with your Indirect Combat Units.
On the Eastern Front don't destroy the Tank that is next to your Medium Tank if it's damaged because if it's too damaged to attack but not damaged enough to retreat, the AI will let it sit there. That said, it's best to have your Rockets pick off alternate targets, such as any Medium Tanks that are behind it.
From here use your Indirect Combat Units to pick off targets one by one until you're able to destroy them one by one. On the Western front be careful that you provide backup for that Tank because it won't last forever, especially if that Artillery gets within range and your Rockets don't hit it, which would be a mistake that would cost you the mission!
Continue to deploy Artillery and Rockets until his Units are weakened, then deploy Tanks to help with the mop-up, or if you want to punch a hole through the South and make a run with an Infantry-loaded APC to capture his HQ you can do that as well.
 Max Day 1
The big difference between using Max here instead of Andy or Sami: he won't be able to reach that Rockets Unit, so a completely different strategy is needed. Move your Rockets and Medium Tank Unit inside of that Rockets Unit's range, but don't fire just yet--if you do it'll get slaughtered. Proceed in a similar manner, shooting at the Artillery with your West Rockets, but deploy a Tank and Infantry to assist with Capturing.
 Max Day 2
Have both Infantry begin capturing both Neutral Cities because you'll need the funds.
On the Western Front, use your Rockets to finish off the approaching Artillery, then Join the fresh Tank with the Damaged Tank, which will give you enough funds to deploy a Medium Tank from your East Base, which is strongly recommended.
On the Eastern Front, have your Medium Tank destroy the Yellow Comet Rockets Unit while your Rockets attack one of his Medium Tanks. If Kanbei doesn't attack your Medium Tank on the East and surrounds it with Tanks, you'll be in good shape.
 Max Day 3 and onward
Finish capturing both Neutral Properties.
On the Eastern front, move your Rockets and Medium Tank one space West each so that the Medium Tank will be on the Bridge with the Rockets Unit directly behind it.
On the Western front have your Rockets fire on the Medium Tank directly behind the damaged Yellow Comet Tank.
At this juncture you don't want to attack because his CO Power Meter will be close to full. Deploy a Tank here and call it a turn.
On Day 4, use your Western Rockets to attack that Medium Tank again. Your Eastern Rockets can either hit the already damaged Medium Tank or a nearby Tank (your call), while your Medium Tank on the Bridge blows the Tank that's next to it away! It's not a bad idea to build an Anti-Air here because of how powerful it will be against enemy Infantry.
Deploy a third Medium Tank on Day 5 to help break down the remaining Units, continuing to fire with your Rockets. If you're worried about the Artillery that's in range on the Western Front here, you can move the Tank back one space, provided that nothing can get past that City (surrounding that City with a Tank and Mech is a good idea.
Now comes the breakout. Start by using the Medium Tank that had been playing defense this whole time to destroy the Tank that's next to it. Next, if an Infantry is in range charge your Anti-Air at it, which will take it out. Now use your second Medium Tank to ruin his remaining Artillery Unit. At this juncture your Rockets can be used to hurt his remaining Medium Tanks.
If he attacked the Western Front with his Units after you built the Medium Tank, send it that way to reinforce the front. If he didn't do that you can send it East to help clean up that front. Either way you'll want to build another Tank Unit here.
If he did choose to wait to attack the Southern Bridge on this turn after moving your new Medium Tank East, you'll still be able to stop him. Use your Rockets to injure the Artillery and proceed to lay a 3-on-1 beatdown on the Medium Tank with your Mech and two Tanks. Use the newly constructed Tank to finish off the wounded Tank on the Southern Bridge.
By this point on the Eastern Front you should be in great shape to start finishing off Units. Keep attacking and Max will win the day!