A subseries of A Certain Magical Index which focus on the scientific side on a side character Level 5 Railgun: Misaka Mikoto with her friends

2 girls having trouble making friends and adapt in school life

Secondary school girls playing board games. (Has a few boys appear in some episode)

A girl who is the only one wear sailor uniform in a western uniform girl school enjoying school life with her friends

A group of maids (mafia???) in Akihabara opening maid cafes and compete to gain more sales

Girls starts survival life on island after plane incident

Girls (Lily) fighting monsters (Huge) with special weapon (Charms) for world peace

Two girls make a promise to find asteriod and story of them with their astrogeo club friend

Girls (Ship) battle

Girls play bands. I recommend to go through 2nd season first as the art and storyline is better than 1st.

If you are more interested on the music instead of story, try Bang Dream Film Live.

Two girls with different background form a team and play golf

A girl of scientist father and ninja grandfather takes revenge on attack that kills her family and steals her father's experiment result

A romance story between two girls who have their own problem.

A shy girl playing guitar with her band mates

Girls playing vr game. (Too bad not all are girls. But most of the characters include main character is girl)

Girls cooking and having meal together.

16 girls working hard to achieve their dream as voice actor. (4 in a group)

Girls having music performance (DJ) in school.

Girls fishing club

Girls making things in DIY club

Comedy daily life between a college girl, a devil summoned by her and the devil's friends.

Girls climbing mountain and hill

A group of girls and non-human helping those who needed to escape from their living area

Girls having sport competition to gain chance for a live concert

Mechanical battle dolls named after guns' names fight for victory

2 girls having their last trip in a destroyed world

3 girls trained to be a healer which can heal people with song. Songs are used frequently to replace dialog.

Girls on battleship

Girls battle (Transform into magic girl)

Two story line.

1. 10 girls becoming idol where they were greatly influenced by a passed away idol

2. The romance story of their male manager and the passed-away idol

Ninja girls having ninja training in a girls only village

Trapped in virtual game world series where she who was once a patient tied to hospital bed, become a royal elf with kids and grandkids

Girls working in cafeteria and their school life

Girls enjoying sport climbing

Reincarnate series where a witch lived 300 years in isekai and finally start making friends and family.

Girls playing band (having teatime in music room) and having happy school life

Girls study to be a member of kageki show (actor)

Girls (Toji) battle monster (Aratama) using special katana

Girls (Yokai) work in a hotel that serve both yokai and human

Trapped in virtual game world series where a girl received gift from GM which is the bear suit.

Girls camping in winter

Strike Witch series without battle but focus on using music to encourage people.

Girls make pottery in school club

Two girls trying to clear the game as savior and return to the real world

10 girls (9 idols and 1 supporter) in school idol club story

Everyday life and fighting against crimes for peace by a secret organisation of girl agents (Lycoris).

A fresh graduate alchemist open a new shop at a small village near the forest

A tired workperson being cured by cute young ghosts

Girl x Gundam. For me, it is first time seeing girls as mains in Gundam series

A racoon (tanuki) learning story-telling of funny story (rakugo) from fox (kitsune) in human town