Besides the Kaiju Stand, the Red Mist is another Stand that can be obtained in the latest Sakura Stand Update. So if you want to know how to get the Stand, here is a detailed guide that explains the entire process.
Getting NEW Kaiju No.8 Spec in Sakura Stand
To get the Red Mist in Sakura Stan, you need to get your kill rate to 100%. First, go to the Q3 NPC in the forest. You can find him in the eastern corner of the forest, right at the start of the Grave POI.
After you find him, interact with him and he will enter a dialogue specifying the kill rate you have taken. Regardless of that rate, all you need to do now is get that kill rate to 100% by eliminating other Hollows, Adjuchas, or Menos NPC enemies in the game. Go to the Hueco Mundo landmark and start eliminating the specified enemies one by one. Eliminating a regular Hollow will scale the kill rate by 1-2%, Meno by 5%, and Adjuchas by 7%. So, according to your specified rate, you will kill the required number of enemies.
Once it's at 100%, go back to the Q3 NPC and he'll tell you that a portal is opening in front of the cafe. Go to the cafe and enter the portal to start a boss fight. There are three phases to the boss fight and survive them all to get the Stand as a drop reward at the end. For the fight, I recommend using something like the Starrk or Binnah as it allows you to fight from a long distance and dodge all of the boss's attacks quite easily. Also, bring your friend along for the fight to have the boss target one player while the other deals free damage to the enemy's blind spot. Repeat this loop of consistently targeting their blind spot and you'll get the Red Mist in no time.