diff --git a/src/boxes/json/mod.rs b/src/boxes/json/mod.rs
index c7d86180..1c789f50 100644
--- a/src/boxes/json/mod.rs
+++ b/src/boxes/json/mod.rs
@@ -6,33 +6,44 @@ use crate::box_trait::{NyashBox, BoxCore, BoxBase, StringBox, BoolBox, IntegerBo
 use crate::boxes::array::ArrayBox;
 use crate::boxes::map_box::MapBox;
 use std::any::Any;
-use std::sync::{Arc, Mutex};
+use std::sync::RwLock;
 use serde_json::{Value, Error};
 
-#[derive(Debug, Clone)]
+#[derive(Debug)]
 pub struct JSONBox {
-    value: Arc<Mutex<Value>>,
+    value: RwLock<Value>,
     base: BoxBase,
 }
 
+impl Clone for JSONBox {
+    fn clone(&self) -> Self {
+        let value_clone = self.value.read().unwrap().clone();
+        
+        Self {
+            value: RwLock::new(value_clone),
+            base: BoxBase::new(), // New unique ID for clone
+        }
+    }
+}
+
 impl JSONBox {
     pub fn from_str(s: &str) -> Result<Self, Error> {
         let value = serde_json::from_str(s)?;
         Ok(JSONBox { 
-            value: Arc::new(Mutex::new(value)), 
+            value: RwLock::new(value), 
             base: BoxBase::new() 
         })
     }
     
     pub fn new(value: Value) -> Self {
         JSONBox { 
-            value: Arc::new(Mutex::new(value)), 
+            value: RwLock::new(value), 
             base: BoxBase::new() 
         }
     }
     
     pub fn to_string(&self) -> String {
-        let value = self.value.lock().unwrap();
+        let value = self.value.read().unwrap();
         value.to_string()
     }
     
@@ -53,7 +64,7 @@ impl JSONBox {
     /// 値取得
     pub fn get(&self, key: Box<dyn NyashBox>) -> Box<dyn NyashBox> {
         let key_str = key.to_string_box().value;
-        let value = self.value.lock().unwrap();
+        let value = self.value.read().unwrap();
         
         if let Some(obj) = value.as_object() {
             if let Some(val) = obj.get(&key_str) {
@@ -79,7 +90,7 @@ impl JSONBox {
     /// 値設定
     pub fn set(&self, key: Box<dyn NyashBox>, new_value: Box<dyn NyashBox>) -> Box<dyn NyashBox> {
         let key_str = key.to_string_box().value;
-        let mut value = self.value.lock().unwrap();
+        let mut value = self.value.write().unwrap();
         
         let json_value = nyash_box_to_json_value(new_value);
         
@@ -94,7 +105,7 @@ impl JSONBox {
     /// キー存在チェック
     pub fn has(&self, key: Box<dyn NyashBox>) -> Box<dyn NyashBox> {
         let key_str = key.to_string_box().value;
-        let value = self.value.lock().unwrap();
+        let value = self.value.read().unwrap();
         
         if let Some(obj) = value.as_object() {
             Box::new(BoolBox::new(obj.contains_key(&key_str)))
@@ -105,7 +116,7 @@ impl JSONBox {
     
     /// すべてのキーを取得
     pub fn keys(&self) -> Box<dyn NyashBox> {
-        let value = self.value.lock().unwrap();
+        let value = self.value.read().unwrap();
         let array = ArrayBox::new();
         
         if let Some(obj) = value.as_object() {
@@ -129,7 +140,7 @@ impl BoxCore for JSONBox {
     }
     
     fn fmt_box(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
-        let value = self.value.lock().unwrap();
+        let value = self.value.read().unwrap();
         let json_type = match *value {
             Value::Null => "null",
             Value::Bool(_) => "boolean",
@@ -166,7 +177,7 @@ impl NyashBox for JSONBox {
     }
 
     fn to_string_box(&self) -> StringBox {
-        let value = self.value.lock().unwrap();
+        let value = self.value.read().unwrap();
         StringBox::new(value.to_string())
     }
 
@@ -178,8 +189,8 @@ impl NyashBox for JSONBox {
 
     fn equals(&self, other: &dyn NyashBox) -> BoolBox {
         if let Some(other_json) = other.as_any().downcast_ref::<JSONBox>() {
-            let self_value = self.value.lock().unwrap();
-            let other_value = other_json.value.lock().unwrap();
+            let self_value = self.value.read().unwrap();
+            let other_value = other_json.value.read().unwrap();
             BoolBox::new(*self_value == *other_value)
         } else {
             BoolBox::new(false)
diff --git a/src/boxes/random_box.rs b/src/boxes/random_box.rs
index e321517d..61bb1f2a 100644
--- a/src/boxes/random_box.rs
+++ b/src/boxes/random_box.rs
@@ -71,16 +71,27 @@ use crate::box_trait::{NyashBox, StringBox, IntegerBox, BoolBox, BoxCore, BoxBas
 use crate::boxes::{ArrayBox, FloatBox};
 use std::fmt::{Debug, Display};
 use std::any::Any;
-use std::sync::{Arc, Mutex};
+use std::sync::RwLock;
 
 /// 乱数生成を提供するBox
-#[derive(Debug, Clone)]
+#[derive(Debug)]
 pub struct RandomBox {
     // 簡易線形合同法による疑似乱数生成器
-    seed: Arc<Mutex<u64>>,
+    seed: RwLock<u64>,
     base: BoxBase,
 }
 
+impl Clone for RandomBox {
+    fn clone(&self) -> Self {
+        let seed_val = *self.seed.read().unwrap();
+        
+        Self {
+            seed: RwLock::new(seed_val),
+            base: BoxBase::new(), // New unique ID for clone
+        }
+    }
+}
+
 impl RandomBox {
     pub fn new() -> Self {
         // 現在時刻を種として使用
@@ -90,7 +101,7 @@ impl RandomBox {
             .as_nanos() as u64;
         
         Self {
-            seed: Arc::new(Mutex::new(seed)),
+            seed: RwLock::new(seed),
             base: BoxBase::new(),
         }
     }
@@ -98,7 +109,7 @@ impl RandomBox {
     /// 種を設定
     pub fn seed(&self, new_seed: Box<dyn NyashBox>) -> Box<dyn NyashBox> {
         if let Some(int_box) = new_seed.as_any().downcast_ref::<IntegerBox>() {
-            *self.seed.lock().unwrap() = int_box.value as u64;
+            *self.seed.write().unwrap() = int_box.value as u64;
             Box::new(StringBox::new("Seed set"))
         } else {
             Box::new(StringBox::new("Error: seed() requires integer input"))
@@ -107,7 +118,7 @@ impl RandomBox {
     
     /// 次の乱数を生成（線形合同法）
     fn next_random(&self) -> u64 {
-        let mut seed = self.seed.lock().unwrap();
+        let mut seed = self.seed.write().unwrap();
         // 線形合同法の定数（Numerical Recipes より）
         *seed = seed.wrapping_mul(1664525).wrapping_add(1013904223);
         *seed
diff --git a/src/boxes/simple_intent_box.rs b/src/boxes/simple_intent_box.rs
index 25df769b..4452b8c8 100644
--- a/src/boxes/simple_intent_box.rs
+++ b/src/boxes/simple_intent_box.rs
@@ -161,21 +161,32 @@
 
 use crate::box_trait::{NyashBox, StringBox, BoolBox, BoxCore, BoxBase};
 use std::any::Any;
-use std::sync::{Arc, Mutex};
+use std::sync::RwLock;
 use std::collections::HashMap;
 
 #[derive(Debug)]
 pub struct SimpleIntentBox {
     base: BoxBase,
     // ノードID -> コールバック関数のマップ
-    listeners: Arc<Mutex<HashMap<String, Vec<String>>>>, // 仮実装
+    listeners: RwLock<HashMap<String, Vec<String>>>, // 仮実装
+}
+
+impl Clone for SimpleIntentBox {
+    fn clone(&self) -> Self {
+        let listeners_val = self.listeners.read().unwrap().clone();
+        
+        Self {
+            base: BoxBase::new(), // New unique ID for clone
+            listeners: RwLock::new(listeners_val),
+        }
+    }
 }
 
 impl SimpleIntentBox {
     pub fn new() -> Self {
         SimpleIntentBox {
             base: BoxBase::new(),
-            listeners: Arc::new(Mutex::new(HashMap::new())),
+            listeners: RwLock::new(HashMap::new()),
         }
     }
 }
@@ -193,6 +204,9 @@ impl BoxCore for SimpleIntentBox {
         write!(f, "SimpleIntentBox(id: {}))", self.base.id)
     }
     
+    fn as_any(&self) -> &dyn Any {
+        self
+    }
     
     fn as_any_mut(&mut self) -> &mut dyn Any {
         self
@@ -217,11 +231,7 @@ impl NyashBox for SimpleIntentBox {
     }
     
     fn clone_box(&self) -> Box<dyn NyashBox> {
-        // IntentBoxは共有されるので、新しいインスタンスを作らない
-        Box::new(SimpleIntentBox {
-            base: BoxBase::new(), // Create new base with unique ID for clone
-            listeners: self.listeners.clone(),
-        })
+        Box::new(self.clone())
     }
     
 }