Memory of the Void

Tobi Otogiri, a second-year student in middle school, doesn't spend much time with his peers. Instead, he mostly chats in secret with his pal Baku, a mysterious backpack he received the day he last saw his older brother. Or at least, Tobi thought his chats were secret until a girl in his class named Ryuuko suddenly mentions Baku. Soon, strange things start happening at school, and the two of them realize the cause might be a creature only they can see… Thus begins an adventure blending reality and fantasy, human and nonhuman—a story about life eating life. (Source: Yen Press)

Otogiri Tobi, a 2nd grade middle school student, spends his depressing days searching for his missing older brother alongside his inhuman companion, Baku. Tobi used to rarely speak to anyone besides Baku, however one day after his classmate Shiratama Ryuuko suddenly approaches him, his life begins to change...? This is an adventure surrounding the "human" and the "inhuman" that a lone boy faces. (Source: Kadokawa, translated)