diff --git a/src/boxes/mod.rs b/src/boxes/mod.rs
index e355c514..d6f57b48 100644
--- a/src/boxes/mod.rs
+++ b/src/boxes/mod.rs
@@ -77,7 +77,7 @@ pub use string_box::StringBox;
 pub use integer_box::IntegerBox;
 pub use bool_box::BoolBox;
 pub use math_box::{MathBox, FloatBox};
-pub use time_box::TimeBox;
+pub use time_box::{TimeBox, DateTimeBox};
 pub use debug_box::DebugBox;
 pub use random_box::RandomBox;
 pub use sound_box::SoundBox;
diff --git a/src/interpreter/expressions.rs b/src/interpreter/expressions.rs
index 3bc31300..1a1cdac0 100644
--- a/src/interpreter/expressions.rs
+++ b/src/interpreter/expressions.rs
@@ -9,7 +9,7 @@
 use super::*;
 use crate::ast::UnaryOperator;
 use crate::boxes::{buffer::BufferBox, JSONBox, HttpClientBox, StreamBox, RegexBox, IntentBox, P2PBox};
-use crate::boxes::{FloatBox, MathBox, ConsoleBox, TimeBox, RandomBox, SoundBox, DebugBox, file::FileBox, MapBox};
+use crate::boxes::{FloatBox, MathBox, ConsoleBox, TimeBox, DateTimeBox, RandomBox, SoundBox, DebugBox, file::FileBox, MapBox};
 use crate::box_trait::BoolBox;
 use crate::operator_traits::OperatorResolver;
 // TODO: Fix NullBox import issue later
diff --git a/src/interpreter/objects.rs b/src/interpreter/objects.rs
index da597b8c..e291f4be 100644
--- a/src/interpreter/objects.rs
+++ b/src/interpreter/objects.rs
@@ -7,7 +7,7 @@
  */
 
 use super::*;
-use crate::boxes::{NullBox, ConsoleBox, FloatBox};
+use crate::boxes::{NullBox, ConsoleBox, FloatBox, DateTimeBox};
 // use crate::boxes::intent_box_wrapper::IntentBoxWrapper;
 use std::sync::Arc;
 
diff --git a/src/interpreter/system_methods.rs b/src/interpreter/system_methods.rs
index 2848b505..403adf23 100644
--- a/src/interpreter/system_methods.rs
+++ b/src/interpreter/system_methods.rs
@@ -11,6 +11,7 @@
 
 use super::*;
 use crate::box_trait::StringBox;
+use crate::boxes::{TimeBox, DateTimeBox};
 
 impl NyashInterpreter {
     /// TimeBoxのメソッド呼び出しを実行
@@ -171,6 +172,14 @@ impl NyashInterpreter {
                 }
                 Ok(datetime_box.addHours(arg_values[0].clone_box()))
             }
+            "toString" => {
+                if !arg_values.is_empty() {
+                    return Err(RuntimeError::InvalidOperation {
+                        message: format!("toString() expects 0 arguments, got {}", arg_values.len()),
+                    });
+                }
+                Ok(Box::new(datetime_box.to_string_box()))
+            }
             _ => {
                 Err(RuntimeError::InvalidOperation {
                     message: format!("Unknown DateTimeBox method: {}", method),
diff --git a/test_datetime_box.nyash b/test_datetime_box.nyash
new file mode 100644
index 00000000..4aea4aaf
--- /dev/null
+++ b/test_datetime_box.nyash
@@ -0,0 +1,43 @@
+// test_datetime_box.nyash - DateTimeBox functionality test
+// Phase 3: DateTimeBox implementation validation
+
+print("📅 Testing DateTimeBox implementation...")
+
+// Basic DateTimeBox creation
+local now, timestamp_dt, parsed_dt, result
+
+// Test 1: Current time creation
+now = new DateTimeBox()
+print("Current time: " + now.toString())
+
+// Test 2: Timestamp creation  
+timestamp_dt = new DateTimeBox(1640995200)  // 2022-01-01 00:00:00 UTC
+print("From timestamp: " + timestamp_dt.toString())
+
+// Test 3: Date component extraction
+result = now.year()
+print("Current year: " + result.toString())
+
+result = now.month()
+print("Current month: " + result.toString())
+
+result = now.day()
+print("Current day: " + result.toString())
+
+result = now.hour()
+print("Current hour: " + result.toString())
+
+result = now.minute()
+print("Current minute: " + result.toString())
+
+result = now.second()
+print("Current second: " + result.toString())
+
+// Test 4: Date arithmetic
+result = now.addDays(7)
+print("7 days from now: " + result.toString())
+
+result = now.addHours(24)
+print("24 hours from now: " + result.toString())
+
+print("✅ DateTimeBox Phase 3 tests completed!")
\ No newline at end of file