Mu Casino Side Quest - Persona 2: Innocent Sin Guides
Mu Casino is one of the more prominent Side Quests in Persona 2: Innocent Sin. You can find Mu Casino in the Yumezaki portion of town, Mu is in the southern portion of the Yumezaki map. As the name should suggest, this place is a Casino so you should expect there to be a fair amount of gambling and luck involved in obtaining the rewards from this quest. The rewards you get from this Casino are one of a kind though and are definitely worth going out of your way to obtain early on in the game.
With that said, there are ways you can decrease the RNG aspects of gambling at Mu Casino, I'll talk more about that below. Mu Casino becomes available after you defeat Principal Hanya in Seven Sister's High at the start of the game. Speak with the various Rumormongers around town and you will learn 3 rumors about Mu Casino which will start this quest:
Toku: It's easy to win at Poker
Toro: It's easy to win the slots
Chikarin: The payout at Blackjack is high
The rumor you choose to spread should depend on your personal preference. If you'd prefer to play Poker then you should spread that rumor, if you'd prefer to play Blackjack then spread that one. Or if you'd like to leave everything up to lady luck and RNG you should spread the one about the slots.
Regardless of the rumor that you spread, once that's done Mu Casino will be open for business. If you plan to play the slots you should talk to people in Yumezaki before heading inside of Mu to learn which slots are hitting. Even if you didn't spread the rumor about it being easy to win at slots that's fine - there will still be someone in Yumezaki who tells you which slot machine is the best to play (pictured below).
Note: Every save file will be different; just because the best slot was #1 for me doesn't mean it'll be the same for you. Make sure you talk to people to learn which slot is good for your save file.
This is the main way to decrease the RNG of gambling in the casino. Aside from this, which rumor you decide to spread can also decrease the RNG. Despite this, we are going to be gambling so there will be some luck involved in the entire process. Another thing to be thankful for though is the LCK stat of your main character will also contribute towards decreasing the RNG while gambling.
As you can probably guess, the better your LCK stat the better your odds of winning. While we're on the topic of winning you may be wondering what's the point in spending time in this Casino anyway -- our goal is to collect Coins because we can then trade the Coins for various prizes.
Mu Casino has a few rewards at the start of the game which are exceptionally good - I will list them all below. One thing to note is later on in the game Mu Casino will add more items to their stock as well; specifically when you reach the point of the game where Jun joins your party. I talk about the best items to buy during both of these periods below.
Mu Casino Default Prizes
Disguise Kit: Decrease encounter rate for a limited time
Items - 1,000 Coins
Luck Source: Lu +1 on level up
Accessory - 10,000 Coins
Vitality Source: Vit +1 on level up
Accessory - 10,000 Coins
Orb of Solving: Analyze unknown fusion skills; when you equip this on your character go through the Fusion Spells menu and you'll see new entries marked with an ??? (if there are potential new skills for you to learn).
Accessory - 3,000 Coins
Styx: Required for summoning the Persona Charon of the Death arcana
Cards - 10,000 Coins
During the first half of the game the only items I think are worth buying from the Casino are listed above. Luck Source and Vitality Source are typically the things I buy first and I keep them on my characters throughout the majority of the game. Vitality Source goes on all 4 of my characters and Luck Source goes on Tatsuya until he gets 15 - 20 levels, then I put Vitality Source on him.
As the items say, Vitality and Luck Source both give you +1 to that stat when leveling up. This is amazingly good and far better than any other Accessory you can get early on in the game. Orb of Solving is neat for unlocking Fusion Skills but not worth it if you are being frugal with coins. Styx is worth skipping too if you're being frugal, it isn't an exceptional Persona or anything like that.
The Disguise Kit item I typically buy a few of because I hate tons of random encounters, especially while writing guides.
Mu Casino Prizes After Xibalba
Desperate Measure: Revive and recover low HP for one ally. Can be used unlimited times, only works in battle.
Item - 8,000 Coins
Star Metal Boots: Give 34 Defense and some Magic Defense too; if you have a lot of extra Coins from gambling then this is a good dump to put them in. I don't recommend it otherwise.
Weapons - 13,000 Coins
Waterlily Petal: Required for summoning the Persona Lakshmi of the Priestess arcana.
Card - 15,000 Coins
General's Piece: Required for summoning the Persona Bishamonten of the Justice arcana.
Card - 14,000 Coins
Healing Card: Adds Diarahan to Persona's Skills. Diarahan is a full heal.
Card - 3,000 Coins
Media Card: Adds Media to Persona's Skills. Media is a group heal.
Card - 2,500 Coins
Recarm Card: Adds Recarm to Persona's Skills.
Card - 3,000 Coins
Maragion Card: Adds Maragion to Persona's Skills. Deals medium fire damage to a group of enemies.
Card - 3,000 Coins
Malaques Card: Adds Malaques to Persona's Skills. Deals medium water damage to a group of enemies.
Card - 3,000 Coins
Magarula Card: Adds Magarula to Persona's Skills. Deals medium wind damage to a group of enemies.
Card - 3,000 Coins
Mamagnara Card: Adds Mamagnara to Persona's Skills. Deals medium earth damage to a group of enemies.
Card - 3,000 Coins