If you're looking for manga similar to Peeping Life x Kaijuu Sakaba: Kaijuu-tachi ga Iru Tokoro, you might like these titles.
Six-graders Boco, Junichi and Joe were enjoying their summer vacation. It was strangely rainless summer, but other than that, it was just like another summer. Three boys knew it was their last summer together. Same summer, deep inside a mine tunnel in New Guinea, an investigation team found something. No one knew they were creatures...terrifying creatures.
One day, an unidentified monster suddenly came out of a volcanic crater near Mt. Fuji, and was given the name "Vulcanus". Lava spews out of its entire body, and as it grows and evolves, the enormous beast's body leaves nothing but scorched earth along its path... Then it makes it to the capital city of Tokyo. Meanwhile, Ichiro Ichinose is a 39-year-old bachelor whose dreams have been shattered and now simply spends his days meaninglessly. After attending a classmate's wedding ceremony, he happens to reunite with his childhood friend Kanata Aida, but after she tells him something that he couldn't possibly understand, the beast arrives and things quickly take a turn for the worse...
Something monstrous rises up from the sea and nearly sinks a Japanese fishing boat. The sole survivor tells a tale that no one wants to believe. But when a Russian nuclear submarine is destroyed in the same waters, the world is forced to face the truth: Godzilla has returned!
High school delinquent—Noroma—with a love for fighting, comes head to head with a giant Kaiju attacking the city! Can his unique martial arts style subdue the threat..?
This incarnation of Ultraman, now called "Tiga," finds the 100-foot tall hero revived in the year 2049 and facing a world ill-equipped to handle the onslaught of gigantic beasts that are peppering the globe. Relying on his martial-arts prowess and his three modes of combat - Sky (flight and speed), Power (strength), and Omni (a balance of the two) - Tiga goes toe to toe with the most terrifying collection of monstrous giants and alien invaders ever to plague the planet.