Mamoru Iwajima (岩島守 Iwashima Mamoru) is one of Kiyo's friends who gained greater importance as the series progressed further on.
He is known to be completely obsessed with catching or seeing UFO's or supernatural things. He is very short and stocky in build, but always sees it as an advantage and never a disadvantage.
While credited and often referred to as "Iwajima" in the English dub, his full name, Mamoru Iwagima, was revealed on Episode 17 of the anime in the English dub.
In chapter 21 of the manga, when Kiyo is explaining all of his friends' talents, he states that Iwajima is "a very interesting guy". Afterward, on the character description page at the beginning of each volume describes Iwashima as "a very interesting guy."