The Anime Lad
Bam has known a dark cave and his friendship with Rachel. When Rachel leaves to climb a Tower said to grant the desires of those who reach the top, he follows her inside. Progress requires passing tests arranged by administrators with limited interest in reassurance. Bam knows almost nothing about the place. The Tower appears satisfied with this admissions standard.
Super Eyepatch Fox
Rachel leaves Bam's sheltered world to climb a mysterious Tower whose summit promises whatever a person desires. Bam follows because she is the only companion he has known. Inside, advancement depends on tests with unfamiliar rules and dangerous competitors. The first episode keeps his motive simple while making the Tower feel vast, withholding explanations so that each door and instruction arrives with a little more uncertainty.
Gigguku
Bam has barely experienced the outside world when Rachel leaves for a Tower that promises your deepest desire. He follows with no map and almost no idea what waits inside. That reckless loyalty gives the opening real charge. Then the tests begin, and every new face seems to know more than he does. I want to open every door with him.
Father's Basement
Tower of God introduces special terms before it has finished introducing the room, which can make mystery feel like missing instructions. Bam's reason for entering is much cleaner. Rachel, the only friend he knows, has gone to climb a Tower that promises desire at its summit, so he follows. The opening tests put that simple motive against rules he does not understand. Confusion works best when the emotional line stays this direct.