This book is a collection of essays on the philosophy of life's meaning in contemporary society. Topics range from antinatalism, meaning of life, the trolley problem, to painless civilization. I am now writing a comprehensive philosophy book on those topics, but it will take several years to complete; hence, I decided to make a handy book to provide readers with an outline of the philosophical approaches to the meaning of life that I have in mind. Chapter One "What Is Antinatalism?" discusses the definition, history, and category of antinatalism. Antinatalism is the thought that all human beings or all sentient beings should not be born. Although I am not an antinatalist, I believe that antinatalism poses an important question about procreation and the meaning of our lives. This is why I presented an overview of antinatalistic thoughts in the past and the present and also performed an analytical examination of their arguments. In Chapter Two "Is Meaning in Life Comparable?," I take up Philosopher Thaddeus Metz's argument on meaning in life, especially his fundamentality theory, and claim that "the heart of meaning in life," which is the concept I propose in this chapter, cannot be compared with anything whatsoever. Chapter Three "What Is Birth Affirmation?" deals with the concept of "birth affirmation," which means that I can say "yes" to my having been born. I believe that birth affirmation is one of the most promising ideas that can contribute to contemporary philosophical discussions on meaning in life, and I call this approach "an affirmation-based approach to meaning in life." The concept of birth affirmation has two dimensions: the psychological dimension and the philosophical dimension. I would like to show in this chapter that it is difficult to clarify what it actually means to say "yes" to my having been born. Chapter Four "The Trolley Problem and the Dropping of Atomic Bombs" discusses the relationship between the dropping of the atomic bombs and the trolley problem. I argue that the dropping of atomic bombs was a typical example of the events that contained the logic of the trolley problem in both their decision-making processes and justifications. I further argue that the trolley problem has its own unique problems, which I call "the problem of the trolley problem." This problem has been overlooked in academic discussions of the trolley problem. I also refer to a religious aspect of this problem. In Chapter Five "Philosophy of Life in Cont