Short answers, pulled from the story.
Osamu Tezuka published the comic on the 2nd of May 1956. This publication marked a quiet revolution in visual storytelling and introduced a new visual vocabulary that prioritized the eye over the body.
A sweat drop floating above a character's head indicates a complex mix of embarrassment, confusion, or social anxiety rather than physical exertion. When a character's eyes turn into spirals, the reader understands dizziness or overwhelming confusion without dialogue.
A throbbing vein depicted as a red cross on the forehead signals a level of anger that transcends mere annoyance. When a character is terrified or shocked, their entire face may shrink, limbs may multiply, and the nose may disappear entirely.
Manga panels are read from right to left following the traditional Japanese writing direction. Artists use speed lines to convey motion and abstract background effects like dense gauze to indicate a mysterious or ominous mood.
The eyes of a character who has died are the color of the iris but darker, while a single large X over the eyes can represent crying rigorously or death. When a character is unconscious or stunned, the eyes may be replaced with X X to convey the state without explanation.