You will not need to play other games in the series before SEII.

Although playing the other games in the series will provide a lot more backstory and character, world and etc development. There isn't a need to play any of them as Solenars Edge II: Aurora of The Seventh Dawn will have a good grasp on the story and will sum up the events of the other games without the need to play them. Allowing the player to jump in blind. For those who have played the other games such as Rebirth and Luvocious. There will be special references and hidden meanings you will understand.

https://store.steampowered.com/app/1283810/Solenars_Edge_II_Aurora_of_The_Seventh_Dawn/