Here are the six Tabby Treasure locations in Yongen-Jaya for the Treasure Tail side quest in Persona 5: The Phantom X. This guide will help you find all of them easily so you can complete the quest and get your rewards.
Where to Find All 6 Tabby Treasures in Yongen-Jaya

The above map of Yongen-Jaya street shows all treasure locations marked by number, so you can find every treasure easily.
1. Start near the cat in Yongen-Jaya. The first treasure is on a trash can to the northwest. Walk over and check the trash can to get it.
2. The second treasure is in some bushes in front of a building. Look for bushes near the street and search between them.
3. For the third treasure, find two gray vending machines that stand next to each other. The treasure is right between them. Stand between the machines and pick it up.
4. The fourth treasure is with a stray cat between the Clinic and the building next to it. You need to buy Tasty Treats Cat Food from the supermarket for 0 yen. Give the food to the stray cat, and you will get the treasure.
5. The fifth treasure is in a flower pot on the street. A man is looking at the pot. Walk up to the pot and check it.
6. The last treasure is in an alley across from the bathhouse. Walk down the alley and you will see a prompt to pick up the treasure.
Once you have found all the Tabby Treasures in Yongen-Jaya, go back to the orange cat and talk to him to complete the quest.