diff --git a/test_array_methods.nyash b/test_array_methods.nyash
new file mode 100644
index 00000000..067bf212
--- /dev/null
+++ b/test_array_methods.nyash
@@ -0,0 +1,65 @@
+// test_array_methods.nyash - ArrayBox改良テスト
+// Phase 1: ArrayBox sort(), reverse(), indexOf(), slice() validation
+
+print("🗂️ Testing ArrayBox improvements...")
+
+// Create and populate array
+local arr
+arr = new ArrayBox()
+arr.push(3)
+arr.push(1) 
+arr.push(2)
+
+print("Original: " + arr.toString())
+
+// Test sort() method
+arr.sort()
+print("Sorted: " + arr.toString())
+
+// Test reverse() method
+arr.reverse()
+print("Reversed: " + arr.toString())
+
+// Test indexOf() method
+local index
+index = arr.indexOf(2)
+print("Index of 2: " + index.toString())
+
+index = arr.indexOf(1)
+print("Index of 1: " + index.toString())
+
+index = arr.indexOf(99)
+print("Index of 99: " + index.toString())
+
+// Test slice() method
+local slice
+slice = arr.slice(0, 2)
+print("Slice [0,2): " + slice.toString())
+
+slice = arr.slice(1, 3)
+print("Slice [1,3): " + slice.toString())
+
+// Test with string array
+local strArr
+strArr = new ArrayBox()
+strArr.push("zebra")
+strArr.push("apple")
+strArr.push("banana")
+
+print("String array original: " + strArr.toString())
+
+strArr.sort()
+print("String array sorted: " + strArr.toString())
+
+strArr.reverse()
+print("String array reversed: " + strArr.toString())
+
+// Test indexOf on strings
+index = strArr.indexOf("apple")
+print("Index of 'apple': " + index.toString())
+
+// Test slice on strings
+slice = strArr.slice(0, 2)
+print("String slice [0,2): " + slice.toString())
+
+print("✅ ArrayBox improvements Phase 1 tests completed!")
\ No newline at end of file
diff --git a/test_cross_type_operators.nyash b/test_cross_type_operators.nyash
new file mode 100644
index 00000000..0951eeb5
--- /dev/null
+++ b/test_cross_type_operators.nyash
@@ -0,0 +1,115 @@
+// test_cross_type_operators.nyash - 演算子システム強化テスト
+// Phase 1: Cross-type operations, string concatenation, comparisons validation
+
+print("🔢 Testing cross-type operators implementation...")
+
+// Test 1: IntegerBox + FloatBox
+print("=== Type Conversion Tests ===")
+local i, f, result
+i = 10
+f = new FloatBox(3.14)
+result = i + f
+print("10 + 3.14 = " + result.toString())
+
+result = f + i
+print("3.14 + 10 = " + result.toString())
+
+// Test multiplication
+result = i * f
+print("10 * 3.14 = " + result.toString())
+
+result = f * i
+print("3.14 * 10 = " + result.toString())
+
+// Test division
+result = i / f
+print("10 / 3.14 = " + result.toString())
+
+result = f / i
+print("3.14 / 10 = " + result.toString())
+
+// Test subtraction
+result = i - f
+print("10 - 3.14 = " + result.toString())
+
+result = f - i
+print("3.14 - 10 = " + result.toString())
+
+// Test 2: String concatenation with numbers
+print("\n=== String Concatenation Tests ===")
+local text, num, boolVal
+text = "Value: "
+num = 42
+boolVal = true
+
+result = text + num
+print("\"Value: \" + 42 = " + result)
+
+result = text + f
+print("\"Value: \" + 3.14 = " + result)
+
+result = text + boolVal
+print("\"Value: \" + true = " + result)
+
+// Reverse concatenation
+result = num + " items"
+print("42 + \" items\" = " + result)
+
+// Test 3: Cross-type comparisons
+print("\n=== Cross-Type Comparison Tests ===")
+local comparison
+
+comparison = f > i
+print("3.14 > 10: " + comparison.toString())
+
+comparison = i > f
+print("10 > 3.14: " + comparison.toString())
+
+comparison = f < i
+print("3.14 < 10: " + comparison.toString())
+
+comparison = i < f
+print("10 < 3.14: " + comparison.toString())
+
+comparison = f >= i
+print("3.14 >= 10: " + comparison.toString())
+
+comparison = i <= f
+print("10 <= 3.14: " + comparison.toString())
+
+comparison = f == i
+print("3.14 == 10: " + comparison.toString())
+
+comparison = f != i
+print("3.14 != 10: " + comparison.toString())
+
+// Test 4: Complex expressions
+print("\n=== Complex Expression Tests ===")
+local complex
+
+complex = (i + f) > 12
+print("(10 + 3.14) > 12: " + complex.toString())
+
+complex = (f * 2) < (i - 3)
+print("(3.14 * 2) < (10 - 3): " + complex.toString())
+
+complex = (i > 5) and (f > 3)
+print("(10 > 5) and (3.14 > 3): " + complex.toString())
+
+complex = (i < 5) or (f > 3)
+print("(10 < 5) or (3.14 > 3): " + complex.toString())
+
+// Test 5: Number to string auto-conversion in concatenation
+print("\n=== Auto-Conversion Tests ===")
+local auto1, auto2, auto3
+
+auto1 = "Result: " + (i + f)
+print("\"Result: \" + (10 + 3.14) = " + auto1)
+
+auto2 = "Boolean: " + (i > f)
+print("\"Boolean: \" + (10 > 3.14) = " + auto2)
+
+auto3 = "Math: " + (f * f)
+print("\"Math: \" + (3.14 * 3.14) = " + auto3)
+
+print("\n✅ Cross-type operators Phase 1 tests completed!")
\ No newline at end of file
diff --git a/test_datetime_tostring.nyash b/test_datetime_tostring.nyash
new file mode 100644
index 00000000..db746198
--- /dev/null
+++ b/test_datetime_tostring.nyash
@@ -0,0 +1,4 @@
+// test_datetime_tostring.nyash - DateTimeBox toString() test as mentioned in issue
+local dt
+dt = new DateTimeBox()
+print(dt.toString())
\ No newline at end of file
diff --git a/test_float_tostring.nyash b/test_float_tostring.nyash
new file mode 100644
index 00000000..e6c596c1
--- /dev/null
+++ b/test_float_tostring.nyash
@@ -0,0 +1,4 @@
+// test_float_tostring.nyash - FloatBox toString() test as mentioned in issue
+local f1
+f1 = new FloatBox(3.14)
+print(f1.toString())
\ No newline at end of file