ig both of them, they are quite similar in some ways
natsuki is more open compared to Akane who is harsh to the MC on the outside, but is kind to everyone else(and obviously likes the MC) she is also a bit shy near her loved ones(+i would assume the the personality that the game dev used in the 0.4.3 for the black Smith shop, the dev used a sentence to give away who he/she was acting as, one of it is "and its not like I've done this for you" which matches the tone and dialogue of Akane)