diff --git a/precompile/binaries/minlib/json.mv b/precompile/binaries/minlib/json.mv
index 06293878..085c0349 100644
Binary files a/precompile/binaries/minlib/json.mv and b/precompile/binaries/minlib/json.mv differ
diff --git a/precompile/binaries/minlib/simple_json.mv b/precompile/binaries/minlib/simple_json.mv
index c3001fe4..58f699ee 100644
Binary files a/precompile/binaries/minlib/simple_json.mv and b/precompile/binaries/minlib/simple_json.mv differ
diff --git a/precompile/binaries/stdlib/json.mv b/precompile/binaries/stdlib/json.mv
index 06293878..085c0349 100644
Binary files a/precompile/binaries/stdlib/json.mv and b/precompile/binaries/stdlib/json.mv differ
diff --git a/precompile/binaries/stdlib/simple_json.mv b/precompile/binaries/stdlib/simple_json.mv
index c3001fe4..58f699ee 100644
Binary files a/precompile/binaries/stdlib/simple_json.mv and b/precompile/binaries/stdlib/simple_json.mv differ
diff --git a/precompile/modules/initia_stdlib/sources/json.move b/precompile/modules/initia_stdlib/sources/json.move
index 42a9d3e8..1b6b3515 100644
--- a/precompile/modules/initia_stdlib/sources/json.move
+++ b/precompile/modules/initia_stdlib/sources/json.move
@@ -232,8 +232,22 @@ module initia_std::json {
             };
             i = i + 1;
         };
-        assert!(i < elem.value.child_length, EKEY_NOT_FOUND);
-        get_next_index(index, i)
+
+        if( i >= elem.value.child_length) {
+            JsonIndex {
+                data: vector::empty(),
+            }
+        } else {
+            get_next_index(index, i)
+        }
+    }
+
+    public fun is_null_index(index: &JsonIndex): bool {
+        if( vector::length(&index.data) == 0) {
+            true
+        } else {
+            false
+        }
     }
 
     fun set_elem(object: &mut JsonObject, index: JsonIndex, elem: JsonElem) {
@@ -747,4 +761,16 @@ module initia_std::json {
         let json_string = stringify(&obj);
         assert!(json_string == string::utf8(b"{}"), 0);
     }
+
+    #[test]
+    fun test_find_key() {
+        let test_str = string::utf8(b"{ \"def\": {\"d\": [-1, 312, \"45.12324\"]}, \"abc\": 18446744073709551615}");
+        let obj = parse(test_str);
+        let index = start_index();
+        let idx = find(&obj, &index, &string::utf8(b"abc"));
+        assert!( !is_null_index(&idx), 0 );
+
+        let idx = find(&obj, &index, &string::utf8(b"a"));
+        assert!( is_null_index(&idx), 1 );
+    }
 }
\ No newline at end of file
diff --git a/precompile/modules/initia_stdlib/sources/simple_json.move b/precompile/modules/initia_stdlib/sources/simple_json.move
index dd7ca757..41557525 100644
--- a/precompile/modules/initia_stdlib/sources/simple_json.move
+++ b/precompile/modules/initia_stdlib/sources/simple_json.move
@@ -5,6 +5,8 @@ module initia_std::simple_json {
     use initia_std::decimal256::{Decimal256};
     use initia_std::string::{String};
 
+    const EKEY_NOT_FOUND: u64 = 0;
+
     struct SimpleJsonObject has copy, drop {
         obj: JsonObject,
         index: JsonIndex,
@@ -70,9 +72,32 @@ module initia_std::simple_json {
         object.index = json::get_next_index(&prev_index, position);
     }
 
+    // to travel object
+    public fun set_to_last_index(object: &mut SimpleJsonObject){
+        let (prev_index, _) = json::get_prev_index(&object.index);
+        let child_length = json::get_child_length(json::borrow(&object.obj, &prev_index));
+        if(child_length == 0) return;
+        object.index = json::get_next_index(&prev_index, child_length - 1);
+    }
+
     public fun find_and_set_index(object: &mut SimpleJsonObject, key: &String) {
         let (prev_index, _) = json::get_prev_index(&object.index);
-        object.index = json::find(&object.obj, &prev_index, key);
+        let find_index = json::find(&object.obj, &prev_index, key);
+        
+        assert!(!json::is_null_index(&find_index), EKEY_NOT_FOUND);
+        object.index = find_index;
+    }
+
+    public fun try_find_and_set_index(object: &mut SimpleJsonObject, key: &String):bool {
+        let (prev_index, _) = json::get_prev_index(&object.index);
+        let find_index = json::find(&object.obj, &prev_index, key);
+        
+        if ( json::is_null_index(&find_index)) {
+            false 
+        } else {
+            object.index = find_index;
+            true
+        }
     }
 
     public fun set_bool(object: &mut SimpleJsonObject, key: Option<String>, value: bool) {
@@ -223,4 +248,50 @@ module initia_std::simple_json {
         let json_string = json::stringify(to_json_object(&obj));
         assert!(json_string == string::utf8(b"{}"), 0);
     }
+
+    #[test]
+    fun test_find_and_set_key0() {
+        let obj = from_json_object(json::parse(string::utf8(b"{}")));
+        increase_depth(&mut obj);
+        let ok = try_find_and_set_index(&mut obj, &string::utf8(b"move"));
+        assert!( !ok, 0);
+
+        set_to_last_index(&mut obj);
+        set_object(&mut obj, option::some(string::utf8(b"move")));
+        increase_depth(&mut obj);
+        set_object(&mut obj, option::some(string::utf8(b"async_callback")));
+
+        let json_str = json::stringify(to_json_object(&obj));
+        assert!( json_str == string::utf8(b"{\"move\":{\"async_callback\":{}}}"), 1)
+    }
+
+    #[test]
+    fun test_find_and_set_key1() {
+        let obj = from_json_object(json::parse(string::utf8(b"{\"move\":{}}")));
+        increase_depth(&mut obj);
+        let ok = try_find_and_set_index(&mut obj, &string::utf8(b"move"));
+        assert!( ok, 0);
+
+        increase_depth(&mut obj);
+        set_object(&mut obj, option::some(string::utf8(b"async_callback")));
+
+        let json_str = json::stringify(to_json_object(&obj));
+        assert!( json_str == string::utf8(b"{\"move\":{\"async_callback\":{}}}"), 1)
+    }
+
+    #[test]
+    fun test_find_and_set_key3() {
+        let obj = from_json_object(json::parse(string::utf8(b"{\"forward\": {\"receiver\": \"chain-c-bech32-address\"}, \"wasm\":{}}")));
+        increase_depth(&mut obj);
+        let ok = try_find_and_set_index(&mut obj, &string::utf8(b"move"));
+        assert!( !ok, 0);
+
+        set_to_last_index(&mut obj);
+        set_object(&mut obj, option::some(string::utf8(b"move")));
+        increase_depth(&mut obj);
+        set_object(&mut obj, option::some(string::utf8(b"async_callback")));
+
+        let json_str = json::stringify(to_json_object(&obj));
+        assert!( json_str == string::utf8(b"{\"forward\":{\"receiver\":\"chain-c-bech32-address\"},\"move\":{\"async_callback\":{}},\"wasm\":{}}"), 1)
+    }
 }
\ No newline at end of file
diff --git a/precompile/modules/minitia_stdlib/sources/json.move b/precompile/modules/minitia_stdlib/sources/json.move
index b8d80b88..502c0d26 100644
--- a/precompile/modules/minitia_stdlib/sources/json.move
+++ b/precompile/modules/minitia_stdlib/sources/json.move
@@ -232,8 +232,22 @@ module minitia_std::json {
             };
             i = i + 1;
         };
-        assert!(i < elem.value.child_length, EKEY_NOT_FOUND);
-        get_next_index(index, i)
+
+        if( i >= elem.value.child_length) {
+            JsonIndex {
+                data: vector::empty(),
+            }
+        } else {
+            get_next_index(index, i)
+        }
+    }
+
+    public fun is_null_index(index: &JsonIndex): bool {
+        if( vector::length(&index.data) == 0) {
+            true
+        } else {
+            false
+        }
     }
 
     fun set_elem(object: &mut JsonObject, index: JsonIndex, elem: JsonElem) {
@@ -747,4 +761,16 @@ module minitia_std::json {
         let json_string = stringify(&obj);
         assert!(json_string == string::utf8(b"{}"), 0);
     }
+
+    #[test]
+    fun test_find_key() {
+        let test_str = string::utf8(b"{ \"def\": {\"d\": [-1, 312, \"45.12324\"]}, \"abc\": 18446744073709551615}");
+        let obj = parse(test_str);
+        let index = start_index();
+        let idx = find(&obj, &index, &string::utf8(b"abc"));
+        assert!( !is_null_index(&idx), 0 );
+
+        let idx = find(&obj, &index, &string::utf8(b"a"));
+        assert!( is_null_index(&idx), 1 );
+    }
 }
\ No newline at end of file
diff --git a/precompile/modules/minitia_stdlib/sources/simple_json.move b/precompile/modules/minitia_stdlib/sources/simple_json.move
index 9d3692ae..0d5bc9c3 100644
--- a/precompile/modules/minitia_stdlib/sources/simple_json.move
+++ b/precompile/modules/minitia_stdlib/sources/simple_json.move
@@ -5,6 +5,8 @@ module minitia_std::simple_json {
     use minitia_std::decimal256::{Decimal256};
     use minitia_std::string::{String};
 
+    const EKEY_NOT_FOUND: u64 = 0;
+
     struct SimpleJsonObject has copy, drop {
         obj: JsonObject,
         index: JsonIndex,
@@ -70,9 +72,32 @@ module minitia_std::simple_json {
         object.index = json::get_next_index(&prev_index, position);
     }
 
+    // to travel object
+    public fun set_to_last_index(object: &mut SimpleJsonObject){
+        let (prev_index, _) = json::get_prev_index(&object.index);
+        let child_length = json::get_child_length(json::borrow(&object.obj, &prev_index));
+        if(child_length == 0) return;
+        object.index = json::get_next_index(&prev_index, child_length - 1);
+    }
+
     public fun find_and_set_index(object: &mut SimpleJsonObject, key: &String) {
         let (prev_index, _) = json::get_prev_index(&object.index);
-        object.index = json::find(&object.obj, &prev_index, key);
+        let find_index = json::find(&object.obj, &prev_index, key);
+        
+        assert!(!json::is_null_index(&find_index), EKEY_NOT_FOUND);
+        object.index = find_index;
+    }
+
+    public fun try_find_and_set_index(object: &mut SimpleJsonObject, key: &String):bool {
+        let (prev_index, _) = json::get_prev_index(&object.index);
+        let find_index = json::find(&object.obj, &prev_index, key);
+        
+        if ( json::is_null_index(&find_index)) {
+            false 
+        } else {
+            object.index = find_index;
+            true
+        }
     }
 
     public fun set_bool(object: &mut SimpleJsonObject, key: Option<String>, value: bool) {
@@ -223,4 +248,50 @@ module minitia_std::simple_json {
         let json_string = json::stringify(to_json_object(&obj));
         assert!(json_string == string::utf8(b"{}"), 0);
     }
+
+    #[test]
+    fun test_find_and_set_key0() {
+        let obj = from_json_object(json::parse(string::utf8(b"{}")));
+        increase_depth(&mut obj);
+        let ok = try_find_and_set_index(&mut obj, &string::utf8(b"move"));
+        assert!( !ok, 0);
+
+        set_to_last_index(&mut obj);
+        set_object(&mut obj, option::some(string::utf8(b"move")));
+        increase_depth(&mut obj);
+        set_object(&mut obj, option::some(string::utf8(b"async_callback")));
+
+        let json_str = json::stringify(to_json_object(&obj));
+        assert!( json_str == string::utf8(b"{\"move\":{\"async_callback\":{}}}"), 1)
+    }
+
+    #[test]
+    fun test_find_and_set_key1() {
+        let obj = from_json_object(json::parse(string::utf8(b"{\"move\":{}}")));
+        increase_depth(&mut obj);
+        let ok = try_find_and_set_index(&mut obj, &string::utf8(b"move"));
+        assert!( ok, 0);
+
+        increase_depth(&mut obj);
+        set_object(&mut obj, option::some(string::utf8(b"async_callback")));
+
+        let json_str = json::stringify(to_json_object(&obj));
+        assert!( json_str == string::utf8(b"{\"move\":{\"async_callback\":{}}}"), 1)
+    }
+
+    #[test]
+    fun test_find_and_set_key3() {
+        let obj = from_json_object(json::parse(string::utf8(b"{\"forward\": {\"receiver\": \"chain-c-bech32-address\"}, \"wasm\":{}}")));
+        increase_depth(&mut obj);
+        let ok = try_find_and_set_index(&mut obj, &string::utf8(b"move"));
+        assert!( !ok, 0);
+
+        set_to_last_index(&mut obj);
+        set_object(&mut obj, option::some(string::utf8(b"move")));
+        increase_depth(&mut obj);
+        set_object(&mut obj, option::some(string::utf8(b"async_callback")));
+
+        let json_str = json::stringify(to_json_object(&obj));
+        assert!( json_str == string::utf8(b"{\"forward\":{\"receiver\":\"chain-c-bech32-address\"},\"move\":{\"async_callback\":{}},\"wasm\":{}}"), 1)
+    }
 }
\ No newline at end of file