Gokinjo Monogatari

Both of them are written by Ai Yazawa so the ambiance feels the same : a group of people making clothes themselves while trying to figure out their dreams. Romance is involved in both, and we follow more the relationship of the male and femal main characters. same kind of humor. If you liked Paradise Kiss, their is not doubt you will also like gokinjo monogatari. 

Kimi ni Todoke has a lot in common with Gokinjo Monogatari. They are both high school love stories, fairly slice of life, and feature adorable chibis. I think the art style is also comparable, though Kimi ni Todoke is certainly a much softer style. If you're looking for a romance and coming of age story, either is a great choice. 

Gokinjo Monogatari is the iconic predecessor of shoujo/josei series like Nana. Both mangas were written by Ai Yazawa. 

Gokinjo Monogatari and Super Gals have very similar feel, both story center around the life of a high school girl and her company, they feature the same themes like romance, friendship and fashion. Both anime are very amusing with a lot of funny moments but have the sad ones as well. 

both has a cute couple that obviuosley needs to be together, but for some reason isn't. both are funny and romantic, and really remind me of each other. 

These series are aimed at a similar audience and are full of nonstop energy and shoujo drama. 

Both main characters are fashion working girls, also focusing on their friend groups and their day to day lives 

From the first episode, Hachimitsu to Clover reminded me of Gokinjo Monogatari. Both has the same setting of art school and both follow the characters as they try to make sense of life, pursue love, and find their place in life. 

Both are heavily stylized classic romance shoujo anime from the 90s with a lot of drama. Both have a primarily school setting, Kareshi Kanojo no Jijou taking place in a regular high school, and Gokinjo Monogatari taking place at an art school. Both anime are very creative in their presentation, with Kareshi Kanojo no Jijou being the more experimental of the two (though Gokinjo Monogatari has more drama between characters). Each anime tells the story of high school girls experiencing their first romances in their own unique ways, and the trials and tribulations that come along with that. The main characters in both anime are also quite determined, one trying to be a perfect student, and the other trying to establish her own fashion brand. Both feature a lot of romance, drama, and classic shoujo goodness. If you enjoyed one you'll likely enjoy the other. read more 

Similar drama, romance situation and art, Both main heroine's have bleached hair and include a self-centered "antagonistic" girl, who causes drama within the series. (Peach Girl has Sae and Gokinjo Monogatari has Mariko)  

Another story of a couple of high school friends who become a couple, involving comedy and drama along the way. This has less side characters but still feels fairly "slice of life" and also deals with the same coming of age issues of leaving school and working out what to do next.