I'd say it's good. The manga has a complex and engaging storyline that keeps you hooked. The art style is also distinctive and adds to the appeal. But be prepared for some intense and emotional moments.
The main plot points start with the existence and nature of Diclonius. Lucy's breakout is crucial as it starts her story in the outside world. Her interactions with Kouta are a big part of the plot, as their relationship is complex and has a lot of history. The research facility's attempts to recapture her and continue their experiments are also significant. Additionally, the exploration of the Diclonius' powers and how they impact the world around them is an important aspect of the overall plot of Elfen Lied.
One way is to create a common threat. For example, a new powerful enemy that neither Naruto's ninja world nor Lucy's world can handle alone. This forces them to team up. Another way is through a portal or some kind of magical/scientific accident that brings them together. Then, the story can unfold as they learn about each other's powers and worlds.
A plot could involve a male Diclonius who discovers he has a unique power among his kind. He is then hunted by other Diclonius who see him as a threat or a valuable asset. As he tries to evade them, he stumbles upon a hidden community of Diclonius who have different ideals and he has to decide whether to join them or continue on his own path. He could also be on a quest to find out the origin of his kind and the true purpose of their powers.
Lucy is a very important character. She is a Diclonius with a tragic past. Her powers are both a curse and a means of survival. Kouta is also important. He has a connection to Lucy's past and his kindness towards her, despite her nature, is a key part of the story. Nana, another Diclonius, plays a significant role as well. She has her own journey of self - discovery and her relationship with the other characters is complex.
One of the main themes is the exploration of human nature. The story delves into the darker aspects of humanity, such as prejudice and fear. Another theme is isolation. The characters, especially the Diclonius like Lucy, are often isolated due to their differences. It also touches on the theme of redemption. Some characters strive to overcome their past mistakes and find a way to be redeemed in the eyes of others and themselves.