diff --git a/src/utils/__tests__/is-false.spec-d.ts b/src/utils/__tests__/is-false.spec-d.ts
new file mode 100644
index 00000000..6609ffc1
--- /dev/null
+++ b/src/utils/__tests__/is-false.spec-d.ts
@@ -0,0 +1,12 @@
+/**
+ * @file Type Tests - isFalse
+ * @module tutils/utils/tests/unit-d/isFalse
+ */
+
+import type testSubject from '../is-false'
+
+describe('unit-d:utils/isFalse', () => {
+  it('should guard false', () => {
+    expectTypeOf<typeof testSubject>().guards.toEqualTypeOf<false>()
+  })
+})
diff --git a/src/utils/__tests__/is-false.spec.ts b/src/utils/__tests__/is-false.spec.ts
new file mode 100644
index 00000000..4e129e33
--- /dev/null
+++ b/src/utils/__tests__/is-false.spec.ts
@@ -0,0 +1,16 @@
+/**
+ * @file Unit Tests - isFalse
+ * @module tutils/utils/tests/unit/isFalse
+ */
+
+import testSubject from '../is-false'
+
+describe('unit:utils/isFalse', () => {
+  it('should return false if value is not false', () => {
+    expect(testSubject(0)).to.be.false
+  })
+
+  it('should return true if value is false', () => {
+    expect(testSubject(false)).to.be.true
+  })
+})
diff --git a/src/utils/__tests__/is-falsy.spec-d.ts b/src/utils/__tests__/is-falsy.spec-d.ts
new file mode 100644
index 00000000..3119a2c1
--- /dev/null
+++ b/src/utils/__tests__/is-falsy.spec-d.ts
@@ -0,0 +1,13 @@
+/**
+ * @file Type Tests - isFalsy
+ * @module tutils/utils/tests/unit-d/isFalsy
+ */
+
+import type { Falsy } from '#src/types'
+import type testSubject from '../is-falsy'
+
+describe('unit-d:utils/isFalsy', () => {
+  it('should guard Falsy', () => {
+    expectTypeOf<typeof testSubject>().guards.toEqualTypeOf<Falsy>()
+  })
+})
diff --git a/src/utils/__tests__/is-falsy.spec.ts b/src/utils/__tests__/is-falsy.spec.ts
new file mode 100644
index 00000000..59c5b734
--- /dev/null
+++ b/src/utils/__tests__/is-falsy.spec.ts
@@ -0,0 +1,38 @@
+/**
+ * @file Unit Tests - isFalsy
+ * @module tutils/utils/tests/unit/isFalsy
+ */
+
+import VEHICLE from '#fixtures/vehicle'
+import testSubject from '../is-falsy'
+
+describe('unit:utils/isFalsy', () => {
+  it('should return false if value is not falsy', () => {
+    // Arrange
+    const cases: Parameters<typeof testSubject>[] = [
+      [1],
+      [true],
+      [VEHICLE],
+      [() => 'hello, world']
+    ]
+
+    // Act + Expect
+    cases.forEach(([value]) => expect(testSubject(value)).to.be.false)
+  })
+
+  it('should return true if value is falsy', () => {
+    // Arrange
+    const cases: Parameters<typeof testSubject>[] = [
+      [0],
+      [0n],
+      [''],
+      [null],
+      [false],
+      [undefined],
+      [Number.NaN]
+    ]
+
+    // Act + Expect
+    cases.forEach(([value]) => expect(testSubject(value)).to.be.true)
+  })
+})
diff --git a/src/utils/__tests__/is-nan.spec.ts b/src/utils/__tests__/is-nan.spec.ts
new file mode 100644
index 00000000..f9b28feb
--- /dev/null
+++ b/src/utils/__tests__/is-nan.spec.ts
@@ -0,0 +1,22 @@
+/**
+ * @file Unit Tests - isNaN
+ * @module tutils/utils/tests/unit/isNaN
+ */
+
+import FLOAT from '#fixtures/float'
+import INTEGER from '#fixtures/integer'
+import testSubject from '../is-nan'
+
+describe('unit:utils/isNaN', () => {
+  it('should return false if value is not Number.NaN', () => {
+    // Arrange
+    const cases: Parameters<typeof testSubject>[] = [[FLOAT], [INTEGER]]
+
+    // Act + Expect
+    cases.forEach(([value]) => expect(testSubject(value)).to.be.false)
+  })
+
+  it('should return true if value is Number.NaN', () => {
+    expect(testSubject(Number.NaN)).to.be.true
+  })
+})
diff --git a/src/utils/__tests__/is-true.spec-d.ts b/src/utils/__tests__/is-true.spec-d.ts
new file mode 100644
index 00000000..c7bfbc17
--- /dev/null
+++ b/src/utils/__tests__/is-true.spec-d.ts
@@ -0,0 +1,12 @@
+/**
+ * @file Type Tests - isTrue
+ * @module tutils/utils/tests/unit-d/isTrue
+ */
+
+import type testSubject from '../is-true'
+
+describe('unit-d:utils/isTrue', () => {
+  it('should guard true', () => {
+    expectTypeOf<typeof testSubject>().guards.toEqualTypeOf<true>()
+  })
+})
diff --git a/src/utils/__tests__/is-true.spec.ts b/src/utils/__tests__/is-true.spec.ts
new file mode 100644
index 00000000..61e49c7d
--- /dev/null
+++ b/src/utils/__tests__/is-true.spec.ts
@@ -0,0 +1,16 @@
+/**
+ * @file Unit Tests - isTrue
+ * @module tutils/utils/tests/unit/isTrue
+ */
+
+import testSubject from '../is-true'
+
+describe('unit:utils/isTrue', () => {
+  it('should return false if value is not true', () => {
+    expect(testSubject(1)).to.be.false
+  })
+
+  it('should return true if value is true', () => {
+    expect(testSubject(true)).to.be.true
+  })
+})
diff --git a/src/utils/includes.ts b/src/utils/includes.ts
index 8aa244ed..5fed517a 100644
--- a/src/utils/includes.ts
+++ b/src/utils/includes.ts
@@ -3,14 +3,8 @@
  * @module tutils/utils/includes
  */
 
-import type {
-  Fn,
-  IfString,
-  NIL,
-  Nilable,
-  NumberString,
-  PropertyKey
-} from '#src/types'
+import type { Fn, IfString, NIL, Nilable, PropertyKey } from '#src/types'
+import cast from './cast'
 import equal from './equal'
 import isString from './is-string'
 
@@ -25,26 +19,30 @@ import isString from './is-string'
  * items to unique keys. If provided, two items with the same identity key will
  * be considered equal.
  *
+ * @todo examples
+ *
  * @template T - Value to search
  * @template K - Identity key type
  *
  * @param {T} value - Value to search
  * @param {unknown} target - Search target
- * @param {Nilable<Fn<[T[0]], K>>} [identity] - Identity key function
- * @param {number | undefined} [position=0] - Position to begin search
- * @return {boolean} `true` if `data` includes `target`
+ * @param {Nilable<Fn<[T[number]], K>>} [identity] - Identity key function
+ * @param {Nilable<number>} [position] - Position to begin search
+ * @return {boolean} `true` if `value` includes `target`
  */
-function includes<
+const includes = <
   T extends string | readonly unknown[],
-  K extends PropertyKey = NumberString
+  K extends PropertyKey = PropertyKey
 >(
   value: T,
   target: unknown,
-  identity?: IfString<T, NIL, Nilable<Fn<[T[0]], K>>>,
-  position: number | undefined = 0
-): boolean {
+  identity?: IfString<T, NIL, Nilable<Fn<[T[number]], K>>>,
+  position?: Nilable<number>
+): boolean => {
+  position ??= 0
+
   return isString(value)
-    ? value.includes(target as string, position)
+    ? value.includes(cast(target), position)
     : value.slice(position).some(item => equal(target, item, identity))
 }
 
diff --git a/src/utils/index.ts b/src/utils/index.ts
index 13da928d..9bb348b5 100644
--- a/src/utils/index.ts
+++ b/src/utils/index.ts
@@ -35,12 +35,15 @@ export { default as isCapitalized } from './is-capitalized'
 export { default as isDate } from './is-date'
 export { default as isEmptyString } from './is-empty-string'
 export { default as isEmptyValue } from './is-empty-value'
+export { default as isFalse } from './is-false'
+export { default as isFalsy } from './is-falsy'
 export { default as isFloat } from './is-float'
 export { default as isFunction } from './is-function'
 export { default as isInteger } from './is-integer'
 export { default as isJsonPrimitive } from './is-json-primitive'
 export { default as isLowercase } from './is-lowercase'
 export { default as isMap } from './is-map'
+export { default as isNaN } from './is-nan'
 export { default as isNIL } from './is-nil'
 export { default as isNodeEnv } from './is-node-env'
 export { default as isNull } from './is-null'
@@ -54,6 +57,7 @@ export { default as isRegExp } from './is-reg-exp'
 export { default as isSet } from './is-set'
 export { default as isString } from './is-string'
 export { default as isSymbol } from './is-symbol'
+export { default as isTrue } from './is-true'
 export { default as isUndefined } from './is-undefined'
 export { default as isUppercase } from './is-uppercase'
 export { default as keys } from './keys'
diff --git a/src/utils/is-empty-value.ts b/src/utils/is-empty-value.ts
index a12ffa05..50487c7a 100644
--- a/src/utils/is-empty-value.ts
+++ b/src/utils/is-empty-value.ts
@@ -8,10 +8,18 @@ import isEmptyString from './is-empty-string'
 import isNIL from './is-nil'
 
 /**
- * Checks if `value` is an empty string, `null`, or `undefined`.
+ * Checks if `value` is an {@linkcode EmptyValue}.
+ *
+ * Empty values include:
+ *
+ * - `''`
+ * - `null`
+ * - `undefined`
+ *
+ * @todo examples
  *
  * @param {unknown} value - Value to check
- * @return {value is EmptyValue} `true` if `value` is empty
+ * @return {value is EmptyValue} `true` if `value` is empty value
  */
 const isEmptyValue = (value: unknown): value is EmptyValue => {
   return isEmptyString(value) || isNIL(value)
diff --git a/src/utils/is-false.ts b/src/utils/is-false.ts
new file mode 100644
index 00000000..d8c2ca2b
--- /dev/null
+++ b/src/utils/is-false.ts
@@ -0,0 +1,18 @@
+/**
+ * @file Utilities - isFalse
+ * @module tutils/utils/isFalse
+ */
+
+import equal from './equal'
+
+/**
+ * Checks if `value` is `false`.
+ *
+ * @todo examples
+ *
+ * @param {unknown} value - Value to check
+ * @return {value is false} `true` if `value` is `false`
+ */
+const isFalse = (value: unknown): value is false => equal(false, value)
+
+export default isFalse
diff --git a/src/utils/is-falsy.ts b/src/utils/is-falsy.ts
new file mode 100644
index 00000000..0ee5b1c4
--- /dev/null
+++ b/src/utils/is-falsy.ts
@@ -0,0 +1,39 @@
+/**
+ * @file Utilities - isFalsy
+ * @module tutils/utils/isFalsy
+ */
+
+import type { Falsy } from '#src/types'
+import includes from './includes'
+import isEmptyValue from './is-empty-value'
+import isFalse from './is-false'
+import isNaN from './is-nan'
+
+/**
+ * Checks if `value` is {@linkcode Falsy}.
+ *
+ * Falsy values include:
+ *
+ * - `''`
+ * - `0`
+ * - `0n`
+ * - `Number.NaN`
+ * - `false`
+ * - `null`
+ * - `undefined`
+ *
+ * @todo examples
+ *
+ * @param {unknown} value - Value to check
+ * @return {value is Falsy} `true` if `value` is falsy
+ */
+const isFalsy = (value: unknown): value is Falsy => {
+  return (
+    isEmptyValue(value) ||
+    isFalse(value) ||
+    isNaN(value) ||
+    includes([0, 0n], value)
+  )
+}
+
+export default isFalsy
diff --git a/src/utils/is-nan.ts b/src/utils/is-nan.ts
new file mode 100644
index 00000000..797a8f6c
--- /dev/null
+++ b/src/utils/is-nan.ts
@@ -0,0 +1,18 @@
+/**
+ * @file Utilities - isNaN
+ * @module tutils/utils/isNaN
+ */
+
+import equal from './equal'
+
+/**
+ * Checks if `value` is {@linkcode Number.NaN}.
+ *
+ * @todo examples
+ *
+ * @param {unknown} value - Value to check
+ * @return {boolean} `true` if `value` is `Number.NaN`
+ */
+const isNaN = (value: unknown): boolean => equal(Number.NaN, value)
+
+export default isNaN
diff --git a/src/utils/is-true.ts b/src/utils/is-true.ts
new file mode 100644
index 00000000..ee542eae
--- /dev/null
+++ b/src/utils/is-true.ts
@@ -0,0 +1,18 @@
+/**
+ * @file Utilities - isTrue
+ * @module tutils/utils/isTrue
+ */
+
+import equal from './equal'
+
+/**
+ * Checks if `value` is `true`.
+ *
+ * @todo examples
+ *
+ * @param {unknown} value - Value to check
+ * @return {value is true} `true` if `value` is `true`
+ */
+const isTrue = (value: unknown): value is true => equal(true, value)
+
+export default isTrue