There are numerous items Kasuga and his party members will probably use during their adventures in Yakusa: Like a Dragon. These items are extremely useful in replenishing your health, MP and removing certain negative effects they may receive during combat. A great way to craft these items yourself rather than purchasing them from one of the shops or restaurants is to plant seeds in garden locations. You won’t immediately gain access to these locations.
To unlocking the planting and garden locations, you need to have visited the Survive bar in the bar district in Yokohama at least once with Adachi. He’ll inform you about how it’s a favorite of it, and it becomes a hangout for you and your party members. If you revisit it during the day, speak to the bartender working behind the counter. After speaking to them, they’ll say they don’t have any use for the plant boxes outside. You’ll also receive a starting batch of tomato seeds from planting there.
Proceed outside and plant the seeds in the pot. These will take a bit of time to grow until you can harvest them. After you plant the seeds, those gardening pots, and others in the city, become available. You can plant any seeds you find or purchase to plant there to grow your own plants. Once you have enough, return to the Survive bar and see what they can craft for you. These items will be useful to replenish your party members and keep them going when battling stronger enemies.
You can purchase seeds from various vendors all over Yokohama, giving you access to several types of plants and vegetables.