I used to buy 4 skills all the time, but gradually I got used to using only 3 skills

Shiranui's discussion, in the reply below, and in the communication with 운화, I have added some information

Shiranui 3's green attack methods are mostly ranged, to avoid adding ineffective melee bonuses to her

You need to operate her seriously because the 3 Green skill does not have blood sucking ability (you must use 3 Green, otherwise she will be very weak). If you encounter survival pressure when challenging any dungeon with a non blood sucking character, please have your supporting character carry (Yasuyama Yachiyo), which will grant you a group healing of 6% of maximum health. If you are in a mechanical challenge, have her use (lthaqua, the White Silence) weapons, This is a very powerful weapon.
People always like popular and powerful characters, ignoring the potential of other characters. There are many characters that can participate in VR battles