diff --git a/scripts/verify-battle-save-normalization.mjs b/scripts/verify-battle-save-normalization.mjs
index 2bfe0a3..9224d91 100644
--- a/scripts/verify-battle-save-normalization.mjs
+++ b/scripts/verify-battle-save-normalization.mjs
@@ -72,6 +72,12 @@ try {
     ['duplicate unit id', { units: [validState.units[0], { ...validState.units[0], x: 2 }, validState.units[2]] }],
     ['invalid bonds', { bonds: [{ ...validState.bonds[0], unitIds: ['liu-bei'] }] }],
     ['unknown bond unit id', { bonds: [{ ...validState.bonds[0], unitIds: ['liu-bei', 'ghost-unit'] }] }],
+    ['invalid bond level', { bonds: [{ ...validState.bonds[0], level: 0 }] }],
+    ['too high bond level', { bonds: [{ ...validState.bonds[0], level: 101 }] }],
+    ['invalid bond exp', { bonds: [{ ...validState.bonds[0], exp: -1 }] }],
+    ['invalid bond exp threshold', { bonds: [{ ...validState.bonds[0], level: 1, exp: 100 }] }],
+    ['invalid max-level bond exp threshold', { bonds: [{ ...validState.bonds[0], level: 100, exp: 101 }] }],
+    ['invalid bond battle exp', { bonds: [{ ...validState.bonds[0], battleExp: 1.5 }] }],
     ['invalid item stock count', { itemStocks: { 'liu-bei': { bean: -1 } } }],
     ['unknown item stock unit id', { itemStocks: { 'ghost-unit': { bean: 1 } } }],
     ['unknown item stock item id', { itemStocks: { 'liu-bei': { phantomItem: 1 } } }],
diff --git a/src/game/state/battleSaveState.ts b/src/game/state/battleSaveState.ts
index ea2f6ff..e784af1 100644
--- a/src/game/state/battleSaveState.ts
+++ b/src/game/state/battleSaveState.ts
@@ -162,6 +162,10 @@ function isNonNegativeFiniteNumber(value: unknown) {
   return typeof value === 'number' && Number.isFinite(value) && value >= 0;
 }
 
+function isNonNegativeInteger(value: unknown) {
+  return Number.isInteger(value) && Number(value) >= 0;
+}
+
 function isFiniteNumber(value: unknown) {
   return typeof value === 'number' && Number.isFinite(value);
 }
@@ -313,13 +317,22 @@ function isBondArray(value: unknown, options: BattleSaveValidationOptions) {
         Array.isArray(bond.unitIds) &&
         bond.unitIds.length === 2 &&
         bond.unitIds.every((unitId) => typeof unitId === 'string' && isKnownUnitId(unitId, options)) &&
-        isPositiveInteger(bond.level) &&
-        isNonNegativeFiniteNumber(bond.exp) &&
-        isNonNegativeFiniteNumber(bond.battleExp)
+        isValidBondProgress(bond.level, bond.exp) &&
+        isNonNegativeInteger(bond.battleExp)
     )
   );
 }
 
+function isValidBondProgress(level: unknown, exp: unknown) {
+  return (
+    isPositiveInteger(level) &&
+    Number(level) <= 100 &&
+    Number.isInteger(exp) &&
+    Number(exp) >= 0 &&
+    (Number(level) >= 100 ? Number(exp) <= 100 : Number(exp) < 100)
+  );
+}
+
 function isOptionalItemStockRecord(value: unknown, options: BattleSaveValidationOptions) {
   if (value === undefined) {
     return true;