diff --git a/zenno/src/lib/data/affinity.ts b/zenno/src/lib/data/affinity.ts
new file mode 100644
index 0000000..8146ed6
--- /dev/null
+++ b/zenno/src/lib/data/affinity.ts
@@ -0,0 +1,35 @@
+import globalJSON from '../../../../global/affinity.json';
+
+/**
+ * Precomputed character pair and trio affinity.
+ */
+export interface Affinity {
+	/**
+	 * First character in the relation.
+	 */
+	chara_a: number;
+	/**
+	 * Second character in the relation.
+	 * chara_a < chara_b is an invariant.
+	 */
+	chara_b: number;
+	/**
+	 * Third character in the relation, if it is a trio relation.
+	 * If defined, chara_b < chara_c is an invariant.
+	 */
+	chara_c?: number;
+	/**
+	 * Total base compatibility between characters in the relation.
+	 */
+	affinity: number;
+}
+
+export const affinity = {
+	global: globalJSON as Affinity[],
+} as const;
+
+export function lookup(aff: Affinity[], chara_a: number, chara_b: number, chara_c?: number): number {
+	const [a, b, c] = [chara_a, chara_b, chara_c ?? Infinity].sort((a, b) => a - b);
+	const r = aff.find((v) => v.chara_a === a && v.chara_b === b && (v.chara_c ?? Infinity) === c);
+	return r?.affinity ?? 0;
+}
diff --git a/zenno/src/lib/data/uma.ts b/zenno/src/lib/data/uma.ts
new file mode 100644
index 0000000..7863457
--- /dev/null
+++ b/zenno/src/lib/data/uma.ts
@@ -0,0 +1,75 @@
+import globalJSON from '../../../../global/uma.json';
+
+/**
+ * Uma or character card definitions.
+ */
+export interface Uma {
+	/**
+	 * Uma ID.
+	 */
+	chara_card_id: number;
+	/**
+	 * Character ID that the Uma is a variant of.
+	 */
+	chara_id: number;
+	/**
+	 * Regional name of the Uma, comprised of the variant name and the character name.
+	 * E.g. "[Special Dreamer] Special Week".
+	 */
+	name: string;
+	/**
+	 * Regional variant name.
+	 * E.g. "[Special Dreamer]".
+	 */
+	variant: string;
+
+	sprint: AptitudeLevel;
+	mile: AptitudeLevel;
+	medium: AptitudeLevel;
+	long: AptitudeLevel;
+	front: AptitudeLevel;
+	pace: AptitudeLevel;
+	late: AptitudeLevel;
+	end: AptitudeLevel;
+	turf: AptitudeLevel;
+	dirt: AptitudeLevel;
+
+	/**
+	 * ID of the Uma's unique skill.
+	 */
+	unique: number;
+	/**
+	 * ID of the Uma's first built-in skill.
+	 */
+	skill1: number;
+	/**
+	 * ID of the Uma's second built-in skill.
+	 */
+	skill2: number;
+	/**
+	 * ID of the Uma's third built-in skill.
+	 */
+	skill3: number;
+	/**
+	 * ID of the skill unlocked at potential level 2.
+	 */
+	skill_pl2: number;
+	/**
+	 * ID of the skill unlocked at potential level 3.
+	 */
+	skill_pl3: number;
+	/**
+	 * ID of the skill unlocked at potential level 4.
+	 */
+	skill_pl4: number;
+	/**
+	 * ID of the skill unlocked at potential level 5.
+	 */
+	skill_pl5: number;
+}
+
+export type AptitudeLevel = 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7;
+
+export const uma = {
+	global: globalJSON as Uma[],
+};
diff --git a/zenno/src/lib/legacy.ts b/zenno/src/lib/legacy.ts
new file mode 100644
index 0000000..2defc00
--- /dev/null
+++ b/zenno/src/lib/legacy.ts
@@ -0,0 +1,72 @@
+import { affinity, lookup } from './data/affinity';
+import { uma, type Uma } from './data/uma';
+
+/**
+ * A legacy, or parents and grandparents.
+ * Defined as an applicative over generic types to reduce the API surface.
+ * @see mapLegacy
+ */
+export interface Legacy<T> {
+	p1: T;
+	s11: T;
+	s12: T;
+	p2: T;
+	s21: T;
+	s22: T;
+}
+
+/**
+ * Applicative fmap for legacies.
+ * @param l Input legacy
+ * @param f Mapping function
+ * @returns Transformed legacy
+ */
+export function mapLegacy<U, V>(l: Legacy<U>, f: (u: U) => V): Legacy<V> {
+	return {
+		p1: f(l.p1),
+		s11: f(l.s11),
+		s12: f(l.s12),
+		p2: f(l.p2),
+		s21: f(l.s21),
+		s22: f(l.s22),
+	}
+}
+
+/**
+ * A veteran, or the result of a completed career.
+ */
+export interface Veteran {
+	uma: number;
+	sparks: number[];
+	saddles: number[];
+}
+
+function findUma(umas: Uma[], u: number): Uma | null {
+	return umas.find((v) => v.chara_card_id === u) ?? null;
+}
+
+/**
+ * Compute individual affinities for a legacy using the global region ruleset.
+ * @param trainee Uma (not character) ID of the trainee Uma
+ * @param legacy Legacy veterans
+ * @returns Individual affinities
+ */
+export function globalAffinity(trainee: number, legacy: Legacy<Veteran>): Legacy<number> {
+	const t = findUma(uma.global, trainee)?.chara_id ?? 0;
+	const charas = mapLegacy(legacy, (u) => findUma(uma.global, u.uma)?.chara_id ?? 0);
+	const saddles = mapLegacy(legacy, (u) => new Set(u.saddles));
+	const aff = affinity.global;
+	const pp = lookup(aff, charas.p1, charas.p2);
+	const s11 = lookup(aff, t, charas.p1, charas.s11) + saddles.p1.intersection(saddles.s11).size;
+	const s12 = lookup(aff, t, charas.p1, charas.s12) + saddles.p1.intersection(saddles.s12).size;
+	const s21 = lookup(aff, t, charas.p2, charas.s21) + saddles.p2.intersection(saddles.s21).size;
+	const s22 = lookup(aff, t, charas.p2, charas.s22) + saddles.p2.intersection(saddles.s22).size;
+	return {
+		p1: lookup(aff, t, charas.p1) + pp + s11 + s12,
+		s11,
+		s12,
+		p2: lookup(aff, t, charas.p2) + pp + s21 + s22,
+		s21,
+		s22,
+	};
+}