Takumi was given gate keys by Lotttie as a form of protection. Each Key is different and has a different sort of power and certain conditions where they can be summoned.
Leo: THe Lion Leader of the Zodiac
Leader of the Zodiac, Leo uses the power of lightning and calls forth power from the star Regulus. He wears a formal suit and sunglasses being very kind and formal to both Takumi and Lottie. He was one of the original keys Takumi got from Lottie.
Virgo: THe Virgin Maid
Virgo is the second of the three main spirits Takumi got from Lottie. She does several things including digging holes, bringing items from Elycian like special clothe and such as well as informing Takumi of different things. Her appearance changes based on her master's preferences.