Rosa Niwa:
a 12 year old girl picked to be the Gardenian red Rose. She a little quirky from time to time but has a heart of gold and friendly towards those who show respect to her .

Her only friend is her adopted sister Amy since she a bit shy around other children and suffers from a traumatic experience where she was excluded from a group of kids in elementary who prefer her sister over her.

She lives with her interracial adoptive parents who also adopted Amy. She has 2 little bothers who are born to her adoptive parents and at home she is loved and accepted by her parents and siblings.

According to Semis she wasn’t suppose to have the flower gardenian leader role and the role was suppose to go to her sister Amy. But Amy isn’t into that and believes Rosa should be confident in the role that was chosen

It later revealed that Rosa came from a magical kingdom Jardin Fleuri and is the long lost daughter of Rosella blanche who sacrificed her self to protect Rosa. From the Thorn King of the wicked weeds

Rosa’s biological father Alstro not much is known of him except he was king of Jardin Fleuri lost his life protecting Rosella and Rosa

Rosa later developed the power of Rose Blanche legacy and can temporarily become Flower Guardian White Rose.( her auburn red hair temporarily turning white)

Semis:
a seedling who was sent to find the Gardenians to bestow their powers

Semis he kinda a jerk to Rosa at first and has tried to take away the red roses pin from her to prevent transformation but the pen ends up back In her hands ,He protested against Rosa being a Gardenian due to a fantasy he had of the right person being the chosen guardian but after seeing Rosa giving it her all and commitment to the leader role he able to accept Rosa as Red rose and apologize for his prejudice was.

He acts a a little guard to Amy and watches out for her under strict orders of Cosmos

….

Yes the misspelling of Guardian is done on purpose for Garden-ian pun