Michel's Ultimate Weapon - Persona 2: Innocent Sin Guides
The quest to get Michel aka Eikichi's Ultimate Weapon can be started once you gain access to the Zodiac Temples towards the end of the game. What you need to do in order to start this quest is make Contact with demons and form Pacts with them; once you've formed the Pact you'll have to ask them for information in subsequent battles.
For those of you who haven't messed with the demon contact system in this game I strongly recommend you read my Making Contact With Demons Guide for more information. Knowing a little bit about how this system works is very important because we'll be using it for this quest and to make Eikichi's weapon stronger in the future.
In order to form a Pact with a demon you'll need to raise their Happy emotion 3 times, once a Pact is formed you'll have to raise Happy 3 times again during a subsequent battle with the same demon. You should check out my Demon Contact - Dialogue Choices Guide for more information about which dialogue choices raise the Happy emotion for each demon.
Eventually one of the demons you've made a Pact with will tell you a rumor about a legendary weapon that is being sold at Shiraishi Ramen located in Kameya Alley in the Hirasaka Prefecture. Once you've acquired this rumor from a demon you'll want to visit Shiraishi Ramen and speak with the lady running the joint.
Choose the small talk option in her dialogue and she'll tell you about the legendary case rumor. Now that we've heard it from her we can head over to the detective agency next door and spread the rumor. Once you've done that return to Shiraishi Ramen and you'll get a scene between Ma'am and Eikichi.
During this scene it's very important you pick the first dialogue option "Good luck." and have Eikichi eat the ramen. If you don't pick this dialogue option then you lock yourself out of getting the legendary case - it's annoying but almost all dialogue options in this game carry significant weight to them.
Once Eikichi has eaten the ramen you'll now be able to purchase the Legendary Case weapon from this shop for 500,000 Yen. That's all there is to obtaining Eikichi's Ultimate Weapon!
One of the unique things about the legendary weapons in Persona 2 is that you can make them stronger by learning rumors from demons and spreading them. After you obtain one of the legendary weapons in this game you'll start to see rumors appear in the 'give me information' dialogue about the weapon you obtained.
Each Legendary Weapon has a total of 6 rumors that you can learn and spread; all of these rumors cancel each other out so you can only spread one of them at a time. Out of all the rumors the best one is definitely "Legendary Weapon is Supreme", this will give your weapon a significant buff once you spread it.
Most of the other rumors will add elemental damage to your weapon and make it deal water, fire, earth or wind damage. Last but not least you have the rumor that your Legendary Weapon is inferior. As you can probably guess, the inferior rumor will lower the damage and quality of the weapon significantly.
1. Legendary Weapon is inferior
2. Legendary Weapon has the power of water
3. Legendary Weapon has the power of fire
4. Legendary Weapon has the power of earth
5. Legendary Weapon has the power of wind
6. Legendary Weapon is supreme
You may be thinking that this all sounds great but it comes with one catch that sounds worse than it really is. Demons can spread a rumor about your Legendary Weapon being inferior and make it a piece of crap... As I said though, this sounds a lot worse than it actually is because demons will very rarely spread this. The only way you can trigger a demon to spread this is if you cause them to be Scared 3 times during battle and they flee.
Even if you make a demon flee from battle it's still not a 100% chance that they'll spread this rumor about your weapon. If this does happen to you though all you need to do is spread one of the other 5 rumors about the weapon to cancel out the inferior one.