Rainbow keys are obtainable through specific requirements in Phantasy Star Online 2. They don’t appear often, but this guide will tell you the best method to add a rainbow key to your inventory.
Earning a rainbow key
A rainbow key is a type of bonus key that you can only get through the PSO2 Mission Pass. When you look at the list for ARKS Missions, you’ll see a category known as Tier Missions. You can complete these objectives weekly to get a set amount of Stars, which, in turn, unlocks more available tiers of rewards.
The rainbow key, officially known as the Bonus Key Tokyo, is available as a reward for Tier 30 on Normal Mode. You may also be able to purchase one for hitting Tier 35 on Overrun Mode. Like other bonus keys, the rainbow key has an expiration date, so you’ll have to take advantage of it no more than seven days (168 hours) after you obtain it.
Keep an eye our for special promotions from Sega, as rainbow keys may be featured as part of a special campaign.