Sachi is an adolescent girl with dark green eyes and long black hair tied into two ponytails.
Sachi is timid and lacking in self-esteem. But she becomes more confident after she won the match in Episode 11.
She is one of Chiari's classmates and Diana's partner-friend.
In Episode 11, she meets Diana after she gets tripped by a group of biking kindergarteners. She tells Diana why she hates sports because when she was in kindergarten, she was being caught by a gluey monster during the competition and made her team became the last.So Diana trains her to be stronger but leaves her after Ruby falls down from the sky and hits her head. Later in the Athletic Day, she is too nervous so she pretends to have a stomachache and escapes. Diana is disappointed when knowing Sachi funks and decides to spoil her own plan, making Sachi upset. However, Diana tells her to persist to the end, which gives her the courage to continue to participate in the relay race. When she trips over Opal's horn, she wants to give up at first but she still runs until she passes the baton to Ruruka because of Diana's encouragement. Although Diana's school loses, both of them understands what is sportsmanship and become friends, which makes them form their first Magic Gem.
In Episode 41, she tries to encourage Diana, who is cursed by the Red Moon. But later, unfortunately, she gets cursed too. After they see Chiari's courage, who is being cheered up and continues to participate, they decides to join back into the competition. They learn "cheering is a power to lift you up when you are down" and their secondary Magic Gems are formed.
She makes a cameo appearance in the graduation ceremony in Episode 52.
- Sachi is Diana's second and last partner.