Tsukiko Yamada is an anime only character who appears in episode 24. She works at a modeling agency that hires Zakuro for their jewelry Fashion shows. Her main job with the agency is to polish all the jewelry that will be used in the shows. She's kind of clumsy and unsure of herself, in some ways even more than Retasu.
Tsukiko has long, medium brown hair that is usually put up in a high ponytail. 3 small strands of her hair stick out on the sides of her head. She has greyish eyes and wears big, round glasses similar to Retasu's. She is usually seen wearing a yellow and white striped shirt, tan baggy pants and sneakers. At the end of the episode she is seen without her glasses, wearing a white, formal dress and her hair is let down giving it a wavy look.
Tokyo Mew Mew
After admiring a pair ring set with her friends, Ichigo goes inside the cafe to find Minto angry at her. Bu-Ling and Retasu explain that since Zakuro's personal assistant is out sick (the English dub changed this to the assistant having a grand piano dropped on her), she wants Ichigo to fill in for her. Minto continues to protest but Zakuro says that it's a matter of strength. Ichigo is then seen lugging a bunch of suitcases and is upset to have even more work dumped on her but then she hears from the other girls that the fashion show is being run by the same company that has the pair ring set and she ends up excited.
While Zakuro is busy with rehearsal, Ichigo sees Tsukiko who accidentally spills a bucket of water, causing the manager to get angry with her and sometime later trying to talk to the fashion show manager about a necklace she's holding but ends up too shy to do so.
That night Ichigo introduces herself and helps her clean up. Tsukiko then tells her about her love of jewelry and how she admires Zakuro but she feels that Zakuro could look even more beautiful modeling jewelry that contains a gem called Rainbow Stone. She believes that the value of a gem isn't the price, but the gems ability to brighten up whoever wears it. Ichigo asks why Tsukiko won't suggest it to the manager and she says that due to her always making mistakes at work, no one will take her word for it. Tsukiko comments that she doesn't have anything radiant about her despite her love for jewelry. It turns out that Zakuro was listening to their conversation secretly.
The next day, Ichigo finds Tsukiko and tells her that if the manager won't accept, maybe Zakuro will. So Tsukiko asks Zakuro if she could wear the Rainbow Stone but Zakuro rejects her. Tsukiko, heartbroken, runs out of the studio. While walking outside, she sees Zakuro in an interview who says that any girl has the ability to shine brightly if they put enough effort in trying. Tsukiko finally understands why Zakuro rejected her and decides to keep trying herself. She then asks the manager to have the Rainbow Stone be modeled in the show, saying that the stone has the power to reveal a girl's true inner beauty, but he just makes fun of her saying that if it's true then she should do it herself and prove it.
Quiche suddenly appears and notices a reaction to the Rainbow Stone with his Mew Aqua piece and attempts to take it. Tsukiko manages to get away only to get knocked out by a Turtle Chimera Anima. Ichigo and the other Mew Mews fight the aliens but in the end it turns out that the stone only reacts to Mew Aqua but it isn't the real thing.After the fight, Zakuro finishes her modeling and she helps Tsukiko dress up in a beautiful white dress, along with the Rainbow Stone necklace and proves to everyone that its power to bring out a girl's inner beauty is true.
Mew Mew Power
In the English dub, Tsukiko's name is changed to Gretchen. Her personality mostly stays true to the original Japanese version but the episode had a few changes involving her character. In the English dub, Gretchen is an intern worker for the agency (in the original, she's an actual employee) and the Rainbow Stone necklace is part of a line of jewelry that she designed herself but no one likes the stone, saying that it's "ugly". After she gains more confidence, she even suggested to the manager that she was willing to model the necklace herself. At the end of the episode, the manager hires her as an full-time model.
- The Mew Mew Power dub hints that Gretchen was born in Ohio.