diff --git a/to-lower-case/Yu-Jaeyoung.py b/to-lower-case/Yu-Jaeyoung.py
new file mode 100644
index 0000000000..1b1fa28c4e
--- /dev/null
+++ b/to-lower-case/Yu-Jaeyoung.py
@@ -0,0 +1,5 @@
+class Solution(object):
+    def toLowerCase(self, s: str) -> str:
+        # Time: O(n), Space: O(n)
+        return s.lower()
+