The 'nee chan wa chuunibyou light novel' might be special for its unique portrayal of chuunibyou elements. It could have interesting characters with over - the - top personalities typical of chuunibyou, like believing they have special powers or are from another world. This often makes for engaging and humorous storylines.
One work that might be similar is 'Love, Chunibyo & Other Delusions'. It also deals with characters having chuunibyou, with a focus on the relationships and the humorous situations that arise from their delusions.
There's not enough information to fully tell the 'Kaya Ghost Assassin' story. However, if we assume, Kaya might be a part of a fictional world where assassins are trained in special techniques. The 'ghost' part could imply that she has the ability to disappear into the shadows, perhaps using some sort of magic or advanced technology. She could be on a mission to avenge someone or to protect a certain secret.
One kaya ghost story could be about a haunted kaya tree. Legend has it that at midnight, a white figure can be seen wandering around the tree. It's said to be the spirit of a young girl who died near the tree long ago.
There could be a sense of relief. Kaya, who has always worried about Usopp during his adventures, would feel relieved to have him back safe, and this relief could turn into a passionate kiss. Usopp, on the other hand, might feel a sense of accomplishment, like he has finally come home to someone who truly cares for him, and that could also be expressed in the kiss.
Well, she might have a unique weapon. Given that she's a ghost assassin, it could be something like a blade that has special powers, perhaps it can phase through solid objects. Also, she may possess enhanced senses, which help her detect her targets even in the darkest of places.
The main plot involves a great conflict. There are different factions vying for power. Kaya, as a key character, is involved in battles and political intrigue. Magic and power struggles are at the core of the story.
One possible storyline could be that after a long separation, Usopp returns to Syrup Village as a hero. Kaya, overjoyed to see him, runs into his arms and they share a spontaneous kiss. This kiss could be the start of a new chapter in their relationship, with Usopp finally realizing his feelings for Kaya are more than just friendship.