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.
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.
The story of Elfen Lied is centered around Lucy. As a Diclonius, she has a tragic past. She was experimented on in a facility. Her escape sets off a chain of events. In the outside world, she is a very dangerous being due to her vectors which can cause great destruction. But beneath her violent exterior, she has a more complex personality. She meets Kouta and his friends. Kouta's family once took care of Lucy when she was a child, which adds an emotional depth to their relationship. The anime also delves into the ethics of the research being done on Diclonius. It shows how society reacts to a being that is different and feared. There are many sub - plots and character developments that make the story engaging and thought - provoking.
Lucy does survive. The manga's ending provides a resolution that leaves her with a chance at a new beginning. There are various factors and plot developments that contribute to her survival.
Definitely not a happy ending. The manga takes some dark turns and doesn't wrap up in a traditional cheerful way. It's more thought-provoking and emotionally charged than just happy.
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.