Introduction:
In the chapter, "The Adventure", Rajendra Deshpande is introduced as a character who is a professor of physics at Mumbai University. However, it is not explicitly stated whether he belongs to the real world or a parallel world.

Real World:
There are several indications in the chapter that suggest that Rajendra Deshpande belongs to the real world. These include:

- His occupation: Rajendra Deshpande is introduced as a professor of physics at Mumbai University. This suggests that he is a real person who holds an academic position in the real world.

- His interactions with other characters: Throughout the chapter, Rajendra Deshpande interacts with other characters who are also from the real world. For example, he has a conversation with his wife, who is also a real person.

- His experiences: The events that Rajendra Deshpande experiences in the chapter are all grounded in reality. He attends a conference, meets with colleagues, and experiences a power outage. There is nothing in the chapter that suggests that he is experiencing anything other than real-world events.

Parallel World:
While there is no conclusive evidence to suggest that Rajendra Deshpande belongs to a parallel world, there are a few details that could be interpreted as such. These include:

- The mysterious book: Rajendra Deshpande receives a book in the mail that he did not order. The book is written in a language that he does not recognize, and it seems to have a strange power over him. This could be interpreted as a sign that he has entered a parallel world, where such magical objects exist.

- The strange occurrences: Throughout the chapter, Rajendra Deshpande experiences several strange occurrences, such as the power outage that seems to be linked to the book. These occurrences could be interpreted as signs that he is experiencing events that are not part of the real world.

Conclusion:
Based on the evidence presented in the chapter, it is most likely that Rajendra Deshpande belongs to the real world. While there are a few details that could be interpreted as signs of a parallel world, there is nothing conclusive to suggest that this is the case.