diff --git a/.changeset/olive-donuts-switch.md b/.changeset/olive-donuts-switch.md
new file mode 100644
index 00000000..b11b2923
--- /dev/null
+++ b/.changeset/olive-donuts-switch.md
@@ -0,0 +1,5 @@
+---
+"@clack/core": patch
+---
+
+Treat an ideographic space (U+3000) committed by IMEs (e.g. Japanese or Chinese input) as space when toggling options in multi-select prompts.
diff --git a/packages/core/src/prompts/group-multiselect.ts b/packages/core/src/prompts/group-multiselect.ts
index e5496728..f68e0fe5 100644
--- a/packages/core/src/prompts/group-multiselect.ts
+++ b/packages/core/src/prompts/group-multiselect.ts
@@ -67,6 +67,13 @@ export default class GroupMultiSelectPrompt<T extends { value: any }> extends Pr
 			this.#selectableGroups ? 0 : 1
 		);
 
+		this.on('key', (char, key) => {
+			// Treat ideographic spaces as if they were normal spaces.
+			if (key.name === undefined && char === '　') {
+				this.toggleValue();
+			}
+		});
+
 		this.on('cursor', (key) => {
 			switch (key) {
 				case 'left':
diff --git a/packages/core/src/prompts/multi-select.ts b/packages/core/src/prompts/multi-select.ts
index 88d76a8e..dd590518 100644
--- a/packages/core/src/prompts/multi-select.ts
+++ b/packages/core/src/prompts/multi-select.ts
@@ -60,13 +60,19 @@ export default class MultiSelectPrompt<T extends OptionLike> extends Prompt<T['v
 			0
 		);
 		this.cursor = this.options[cursor]?.disabled ? findCursor<T>(cursor, 1, this.options) : cursor;
-		this.on('key', (_char, key) => {
+		this.on('key', (char, key) => {
 			if (key.name === 'a') {
 				this.toggleAll();
 			}
 			if (key.name === 'i') {
 				this.toggleInvert();
 			}
+			// Some IMEs (e.g. Japanese or Chinese input) commit an ideographic space (U+3000)
+			// with no key name when the space key is pressed. Treat it as space so
+			// toggling options still works.
+			if (key.name === undefined && char === '　') {
+				this.toggleValue();
+			}
 		});
 
 		this.on('cursor', (key) => {
diff --git a/packages/core/test/prompts/group-multiselect.test.ts b/packages/core/test/prompts/group-multiselect.test.ts
index fa370f7f..755bbf0c 100644
--- a/packages/core/test/prompts/group-multiselect.test.ts
+++ b/packages/core/test/prompts/group-multiselect.test.ts
@@ -30,6 +30,24 @@ describe('GroupMultiSelectPrompt', () => {
 		expect(output.buffer).to.deep.equal([cursor.hide, 'foo']);
 	});
 
+	test('toggles option with ideographic space (U+3000) committed by IME', () => {
+		const instance = new GroupMultiSelectPrompt({
+			input,
+			output,
+			render: () => 'foo',
+			options: {
+				group: [{ value: 'foo' }, { value: 'bar' }],
+			},
+			selectableGroups: false,
+		});
+		instance.prompt();
+
+		input.emit('keypress', '　', { sequence: '\u3000' });
+		expect(instance.value).toEqual(['foo']);
+		input.emit('keypress', '　', { sequence: '\u3000' });
+		expect(instance.value).toEqual([]);
+	});
+
 	test('does not throw if empty options are provided', () => {
 		const instance = new GroupMultiSelectPrompt({
 			input,
diff --git a/packages/core/test/prompts/multi-select.test.ts b/packages/core/test/prompts/multi-select.test.ts
index e8af630d..edef73e4 100644
--- a/packages/core/test/prompts/multi-select.test.ts
+++ b/packages/core/test/prompts/multi-select.test.ts
@@ -143,6 +143,21 @@ describe('MultiSelectPrompt', () => {
 			expect(instance.value).toEqual(['foo']);
 		});
 
+		test('toggles option with ideographic space (U+3000) committed by IME', () => {
+			const instance = new MultiSelectPrompt({
+				input,
+				output,
+				render: () => 'foo',
+				options: [{ value: 'foo' }, { value: 'bar' }],
+			});
+			instance.prompt();
+
+			input.emit('keypress', '　', { sequence: '\u3000' });
+			expect(instance.value).toEqual(['foo']);
+			input.emit('keypress', '　', { sequence: '\u3000' });
+			expect(instance.value).toEqual([]);
+		});
+
 		test('disabled options are skipped', () => {
 			const instance = new MultiSelectPrompt({
 				input,