The Seven Deadly Sins
七つの大罪 · Nanatsu no Taizai
Nanatsu no Taizai · convention
A Christian catalogue of vices, imported into manga as a naming scheme for seven-member teams.
Filed by its count, not its title
Reduced as a phrase, “The Seven Deadly Sins” would sit on The Telling — but that would be reducing wording this reference chose. The set is filed under 7 · The Inquiry instead, because 7 is what its author chose, and a chosen number outranks an imposed one.
What it is
Pride, greed, lust, envy, gluttony, wrath and sloth — a mediaeval Christian taxonomy of vice, adopted in manga as a ready-made set of seven names with built-in personalities.
What the number does
Very little on its own; the value is entirely in the labels. This is the opposite of a taxonomy that carries rules. Nothing about the seven sins constrains what a character can do, and the set imposes no ranking, so an author who adopts it gets seven distinct silhouettes and no obligations.
That cheapness is why it recurs. A borrowed set with strong names and weak rules is the most economical thing an author can pick up.
Christianity as set-dressing
Western religious material enters Japanese popular fiction largely stripped of doctrine and kept for its imagery — crosses, angel ranks, the sins. This reference notes it without complaint: it is the same operation manga performs on Chinese divination in the Eight Gates, and Western fiction has been doing it to Japanese material for just as long.