If you're looking for manga similar to Nansensu Monogatari Daiichi-hen: Sarugashima, you might like these titles.
Megumi is currently working on her master's thesis in cultural studies. She wants to research indigenous tribes but footage and literature at the university can only get her so far. So when her idol Professor Rukawa offers her a chance to come with him to Africa to conduct research on the local Kugul tribe, Megumi agrees. Two months later, Megumi sets foot in Africa and meets Kugul warrior Barut who saves her and Professor Rukawa from a leopard. From there, Megumi finds herself getting closer with Barut, the latter being more touchy than what she bargained for. Will cultural differences be in the way of their chance at love?
Haré and his mother live peacefully in the jungle, until one day the boy is overtaken by a omnipotent shadow. Later, he awakens to find Guu, a strange girl with even stranger abilities - notably, the ability to switch from a cute, lovable Guu, to a menacing delinquent who eats everything. Now Haré must live with Guu, and lead a normal life, despite her oddities.
Eve gets dragged into an armed conflict deep in the jungle, escorted by field unit major Wade O'Mara. Wade is strong, and he shields her from the terrors of war. I want to know more about you, Eve thinks. She's known nothing of love before this, but now she begins to feel that passionate emotion for the first time in her life. "If I'm with you, even a battlefield can be Eden..."
1947, South American Amazon. A boy named Tommy, brought up in the jungle, is separated from his father, who is exploring ancient ruins. Before him, the beautiful girl Shanana apears. Having no common sense, the daring and slightly ecchi Shanana startled Tommy. But soon, the two's encounter will shake the world...?
Hunters beware! Tar-chan, king of the jungle, protects the animals from those who would capture or kill them. And with a bounty on his head, life isn't easy for the muscular hunk. Whether he's fighting poachers and bounty hunters, taking care of the whims of his once-model-now-fat wife Jane, entertaining the advances of nubile teenager Helen or fighting with his archrival Anabebe, Tar-chan's life is never dull.
As the future emperor of the African jungle, Leo the lion cub is sent off to live with a little Japanese boy named Kenichi. During his stint with the humans, Leo has many learning experiences and somehow always manages to get into a little trouble along the way. But when a rat arrives—carried by a stork like a little bundle of joy, no less—with a message from home, Leo realizes it’s time to return to the jungle. As he embarks on his biggest adventure yet, he’s unaware of the great battles that lie ahead.