Here are 10 underrated manga series you should definitely check out:

1. Frieren: Beyond Journey's End (Genre: Fantasy, Adventure)

This story follows a party of adventurers years after they've defeated the Demon King. The Elf mage Frieren watches as her companions age and die, due to her long lifespan. It's a beautiful and introspective look at life, death, and friendship.

2. Dorohedoro (Genre: Action, Dark Fantasy)

In a dystopian world divided by a giant hole,  the magic-users of the Hole experiment on the citizens of the land above.  A badass amnesiac cyborg named Kaiman and his reptilian friend Nikaido seek revenge on the sorcerers who turned Kaiman into a lizard-man. This manga is a wild ride with a great story and unforgettable characters.

3. Akatsuki no Yona (Genre: Historical Fantasy, Romance)

The sheltered princess Yona is thrust into a world of violence when her kingdom is betrayed. With her loyal bodyguard Hak by her side, she must find the five legendary Dragon Warriors to reclaim her throne. This is a great story about a girl who learns to be strong and independent.

4. The Promised Neverland (Genre: Mystery, Sci-Fi, Thriller)

Emma, Norman, and Ray are the brightest kids at Grace Field House, an idyllic orphanage. However, they soon discover a dark truth about the orphanage and the horrifying fate that awaits its residents. This is a gripping story with plenty of twists and turns.

5. Beastars (Genre: Drama, Mystery, School Life)

In a world where carnivores and herbivores live together in an uneasy truce, a gray wolf named Legoshi falls in love with a dwarf rabbit named Haru. This is a complex and thought-provoking story that explores themes of prejudice, violence, and love.

6. Land of the Lustrous (Genre: Adventure, Fantasy, Sci-Fi)

In the distant future, the Earth is covered in gemstones. The story follows Phos, a new gem who is too weak to fight and struggles to find their place in the world. This is a beautiful and strange story with a unique world and complex characters.

7. Yokohama Kaidashi Kikou (Genre: Slice of Life, Science Fiction)

This post-apocalyptic slice-of-life story follows a cyborg named Alpha who runs a small coffee shop in a deserted city. It's a slow-paced and meditative story about the beauty of everyday life.

8. Oshi no Ko (Genre: Drama, Mystery, Showbiz)

Goro Adachi is a reclusive manga artist who dies young. He's reincarnated as the son of his biggest fan, a single mother who once dreamed of becoming an idol herself. This is a fascinating story about the entertainment industry and the power of dreams. 

9. Sakamoto Days (Genre: Action, Comedy)

A legendary hitman named Sakamoto just wants to live a normal life. However, trouble keeps finding him. This is a hilarious and action-packed story with a great cast of characters.

10. Dandan Dan (Genre: Action, Romance, Sci-Fi)

Momo Ayase wants to prove aliens are real.  Kenichi Oguro wants to prove supernatural abilities are real.  When they both gain strange powers, they team up to investigate the occult and uncover the truth. This is a fun and exciting story with a great central duo.