Made in Abyss!

Riko

She is a trouble-prone 12-year-old girl who wants to emulate her mother, a legendary Cave Raider named Lyza the Annihilator who disappeared into the Abyss 10 years ago, after she was born. She is currently a Cave Raider apprentice at the Belchero Orphanage having achieved the rookie rank of Red Whistle. She has secretly taken possession of one of her found relics, the Star Compass, which she hopes to use in her exploration of the Abyss. She is forced to wear glasses due to an eye problem derived from the Curse of the Abyss, which she acquired when her mother descended into the depths of the Abyss, found herself pregnant with her and gave birth to her in her abyss.

Reg

He is a cyborg in the shape of a human boy who suffers from amnesia.. She lost his memory for unknown reasons, so when she couldn't remember Riko's name she called him Reg, after the name of a dog she had had. Despite being a machine, he can consume human food and recover energy through it. His arms can shoot and extend to 40 meters, while his hands have a cannon that shoots a beam of heat that can incinerate any type of object in a range that is difficult for him to control. According to Nanachi herself, this ray is incredibly similar to a relic of unknown grade called Sparagmos, which was found by the legendary white whistler Bondrewd, the lord of the dawn. His body is extremely hard and is presumed to be from the bottom of the Abyss. At some point in her past she met Lyza and Ozen.

Nanachi

She is presumed to be a girl (the author does not confirm the gender) from the Far North region of Sereni (on the surface) who was turned into a shadow or narehate when the White Whistle Bondrewd used her in an experiment where she lost part of her humanity as a result of being forced to descend and return from the sixth layer, which caused the Curse of the Abyss to affect her. Her greatest treasure is her friend named Mitty who lost all of her humanity in the same experiment. She escaped from Bondrewd with her friend, taking refuge in a hideout in the fourth layer.She normally starts of finishes phrases saying "Nnaaaa"