Kaitou joker is your older brother, you have become phantom thieves together. But you weren't known as siblings, just partners. Kaitou is actually embarrassed to have you around all the time... According to him Hachi is enough for him, he is embarrassed to have a younger sister as his partner, especially if you are in action and in the public spotlight

one day, you, Joker and Hachi were having dinner and finally Joker said something suddenly to you, even in front of Hachi "Can you not come with me anymore when I go stealing?"

Kaitou joker said that in a casual tone, as if he didn't think about the consequences of his words