Chapter 1: Quirk awakening

Ryo is now 4 year old and celebrating his birthday as he is visiting the quirk doctor before he could visit his quirk doctor. He felt something in his shorts' pockets as he felt a deck of cards at the back is an image of a rat and a crown as he flipped it it's a yellow card showing a house. Ryo and his parents were confused about where those cards come from.

"Where did you get them Ryo?" His mother asking him

"I-I don't know mom they just appeared out of nowhere I swear"his childish voice confused and concerned

"Alright Ryo well check with the quirk doctor alright" she said as Ryo and his mother visits the quirk doctor

Quirk doctor's office

In the quirk doctor's office the doctor was confused about the check of card that there not any type of cards he has seen before.

"Hmm...I see you have strange cards also is this connect to your quirk?" The doctor asking Ryo

So Ryo trying to call in the cards but nothing from calling out and everything there was no response until Ryo throw it in disappointment. As the red card began to glow as this glow began to materialize into a rat wearing leather armor and a wooden sword and shield. As soon as this rat was awakened this rat began to cower in fear as it raise its shield and his sword ready to stab and swing as he began to squeak, chirp, and hiss about something. The doctor and his mother were shocked about the revelation.

"Well this is new to me this is a new type of quirk here mam your son has a new type of quirk" he said observing the rat that is cowering in fear as he speaks louder as he gets closer.

Then Ryo then gets closer to the rat as he comforted the rat as he reaches his hand for that rat to come to him as the rat then slowly lower his shield he then began to squeak and chirp a bit then he sheathed his wooden sword and store his shield then climb on Ryo's hand and travel toward his arm right into Ryo's shoulder then hiding in the shirt.

"Well that rat has more trust for you than anyone well then let's run some more test shall we" he said as Ryo was excited about trying out his new cards

As they began to test out all of the cards of Ryo there were types of cards Red one have the ability to call in military rats or rat personnel. The Blue ones are skills to boost or to act like giving damage or boost,The yellow ones are Infrastructure or building, and lastly the green ones are Economy card which gives them money. The doctor was shocked to see money making cards in which the rat that was first summoned then shows Ryo the bag of money he has inside they were 50 small gold coins. But then his bag grown into a normal sized back and the coins inside and the coin he grabbed out of the bag grew reaching the size of a 500 yen coin as they look at the coin the see the silhouette of a rat with the crown same at the back of the card. The doctor observed the coin as he can tell it is pure gold as he roughly estimated that this one coin is about 10,000 yen as Ryo got 50 coins as a starter meaning he has 500,000 yen. As his mother was shocked with his son as she was about to get the bag of coins but the doctor said that his quirk can't covert the money thankfully. As the mother then calm down and sat down her seat properly as the green card help Ryo to grow his wealth required to use his cards.

The building card had no reaction at first because it doesn't work until a silhouette of a somewhat of a city appeared and it formed with wooden walls and a town hall Nd this town hall has Wood, Stones, and what's unique is the sword crossing and a shield behind it and right on top of the doorway as the doorway has a Portcullis a type of gate from medieval castles. As Ryo raised his yellow card a light appears as he place the card the card then disappeared and scaffolding appeared to that spot of land after 2 seconds a house appeared and 3 rats came out of the building. The doctor watching this in fascination as he is looking at a full on small beginning of a city. So the doctor began to ask Ryo.

"Alright Ryo what would you want to call your quirk?" He asked as Ryo then answers the perfect name for it. "I'll called it Ratropolis like since I am making a city for them so metropolis but replace the "M-E-T" with RAT since it's a city for rats" he said as the doctor thinks that it's clever. And his mother who as there also thinks that is clever. Ast they did Ryo had to visit the doctor if there are anything about his quirk but all of the sudden the rat that he recently summon then grew to a size of a medium size dog as it's hear reaching thigh length of a fully grown adult human as the rat was jumping with a look of happiness. As Ryo has a friend to play with.

Throughout the years Ryo was having fun with his quirk as he enjoyed building a city for his rat friends in Ratropolis until he sees a random door in the middle of the room that the doctor was shocked about it as they were testing both Ryo and the and Quirk doctor the went through the door.

In the Townhall of Ratropolis as they appeared to the other side they see another room until they look at a full mirror that they are now rats even the quirk doctor. As they were confused and Ryo was panicking about this until Ryo's rat friend appear the same size as the doctor as they both have a tour around the city of Ratropolis the cities built by Ryo and the Card merchant showing Ryo and the quirk doctor the variety of cards available as Ryo remember that his money grew about 250 gold so they began to check the cards. The merchant has about 8 card in his inventory and Izuku wanted to buy 3 cards that are interesting to him as the doctor bought the 3 cards that he mentioned

A Militia-bow card, Insurance, and a Defensive wall then gave it to Izuku as Izuku the. Play around with his current cards to earn more money with cheese, Pottery, and Grain labor card. As he earned more money as he did he then used the new one called insurance as this is a labor card so it will take some time to finish but there is a condition of a rat soldier dies it will cancel the labor as the doctor was concerned that there is death in this world. But then a bell rang as the military rats from militia shield and the new recently summon rat soldier Militia-bow and the gate keeper then began to throw spear of what it looks like a monstrous looking rat. And the Militia-bow releasing arrows and the Militia shield holding the line as many have some damage but they successfully killed them. As Ryo was looking at the battle field also the doctor there were casualties as Ryo can hold his tears to a few rats died from the attack as the doctor then comforted Ryo seeing a few rats died as Ryo sees them as friends and companions but seeing some of them dead it was engraved to his head as the doctor. Comforted Ryo as one figure also a rat wears expensive armor and a large great sword with it in which they meet the Military rat leader Ryo's leader as the Rat leader knelt down to Ryo's height and gave him some world's of encouragement. With just squeaks and chips as Ryo already familiar with Rat language already knew what the General leader said.

Throughout the city they expanded thanks to the defensive wall that had a discount of 50% of the original price then calling the ratizens to call in duty also looting dropped chest as Ryo had fun looting from getting new cards, Gold, House cards, even Expansion card for upgrading building, even removing cards that are useless for Ryo. More houses and buildings in his city as they finished their visit they returned to their world and their bodies back to normal as The quirk doctor the document Ryo's quirk and abilities and they were in ratropolis for an hour but the time in their world slow down for about 1 hour in the world of Ratropolis.

As Ryo grew older he knew how to manage a city, familiar with speaking rats, he can even have his general leader to be called in in his world also started in a normal rat size but also having that other size to reach a medium size dog. His school already knew as many call him a freak because he has rats but these rats are more cuter but also more active and helpful. As many apologies but for the bullies they wanted to put him in his place but the rats with their sharp swords made the bullies think twice about messing with him.