be open and easy to get on with

My older sister has an open nature.

私の姉はさっぱりした性格です

My older sister usually has an open nature.

私の姉は普段、さっぱりした性格です

My older sister usually has an open nature even with people she has just met.

私の姉は普段、初めて会った人ともさっぱりした性格です

My older sister usually has an open nature, getting close quickly even with people she has just met.

私の姉は普段、初めて会った人ともすぐ親しくなるほどさっぱりした性格です

My older sister usually has an open nature among her friends, getting close quickly even with people she has just met.

私の姉は普段、初めて会った人ともすぐ親しくなるほど友達の間でさっぱりした性格です