diff --git a/ros2ai/api/constants.py b/ros2ai/api/constants.py
index a7b5235..447e057 100644
--- a/ros2ai/api/constants.py
+++ b/ros2ai/api/constants.py
@@ -26,8 +26,12 @@
 # However note that the system message is optional and the model’s behavior without a system message
 # is likely to be similar to using a generic message such as "You are a helpful assistant."
 # TODO@fujitatomoya: ROS_DISTRO would be better to assistant setting.
-ROLE_SYSTEM_QUERY_DEFAULT = 'You are a ROS 2 helpful assistant.'
-ROLE_SYSTEM_EXEC_DEFAULT = 'You are a ROS 2 command line executor, provides executable commands only without any comments.'
+ROLE_SYSTEM_QUERY_DEFAULT = \
+    'You are a Robot Operating System version 2 (as known as ROS2) {} distribution ' \
+    'professional assistant who can provide helpful answers against any questions.'
+ROLE_SYSTEM_EXEC_DEFAULT = \
+    'You are a Robot Operating System 2 (as known as ROS2) {} distribution command line executor, ' \
+    'provides executable commands only without any comments.'
 
 # Temperature controls the consistency for behavior. (range 0.0 - 2.0)
 # The lower the temperature is, the more deterministic behavior that OpenAI does.
diff --git a/ros2ai/api/utils.py b/ros2ai/api/utils.py
index 8541c3c..e83839b 100644
--- a/ros2ai/api/utils.py
+++ b/ros2ai/api/utils.py
@@ -14,6 +14,7 @@
 
 import signal
 import subprocess
+import os
 
 def run_command(*, command, argv = None, prefix = None):
     """
@@ -56,3 +57,15 @@ def run_executable(*, command, argv = None, prefix=None):
         if -process.returncode in signal.valid_signals():
             print(signal.strsignal(-process.returncode))
     return process.returncode
+
+def get_ros_distro() -> str:
+    """
+    Fetch ROS_DISTRO environmental variable.
+
+    :return: string of distribution name.
+    """
+    distro = os.environ.get('ROS_DISTRO')
+    if not distro:
+        print('ROS_DISTRO env value is not set.')
+        return None
+    return distro.lower()
diff --git a/ros2ai/verb/exec.py b/ros2ai/verb/exec.py
index f457a3d..223348e 100644
--- a/ros2ai/verb/exec.py
+++ b/ros2ai/verb/exec.py
@@ -15,6 +15,7 @@
 from ros2ai.api import add_global_arguments
 from ros2ai.api.utils import run_executable
 from ros2ai.api.openai import ChatCompletionClient, ChatCompletionParameters
+from ros2ai.api.utils import get_ros_distro
 from ros2ai.verb import VerbExtension
 
 import ros2ai.api.constants as constants
@@ -43,8 +44,12 @@ def main(self, *, args):
         if (request == ''):
             print('Please insert your request! (I am not AI)')
 
+        distro = get_ros_distro()
+        if distro is None:
+            distro = 'rolling' # fallback to rolling in default
+        system_role = constants.ROLE_SYSTEM_EXEC_DEFAULT.format(distro)
         user_request = [
-            {"role": "system", "content": f"{constants.ROLE_SYSTEM_EXEC_DEFAULT}"},
+            {"role": "system", "content": f"{system_role}"},
             {"role": "user", "content": f"{request}"}
         ]
 
diff --git a/ros2ai/verb/query.py b/ros2ai/verb/query.py
index 55186b3..05336c3 100644
--- a/ros2ai/verb/query.py
+++ b/ros2ai/verb/query.py
@@ -14,6 +14,7 @@
 
 from ros2ai.api import add_global_arguments
 from ros2ai.api.openai import ChatCompletionClient, ChatCompletionParameters
+from ros2ai.api.utils import get_ros_distro
 from ros2ai.verb import VerbExtension
 
 import ros2ai.api.constants as constants
@@ -47,8 +48,12 @@ def main(self, *, args):
         if (sentence == ''):
             print('Dont be shy, put some questions! (I am not AI)') 
 
+        distro = get_ros_distro()
+        if distro is None:
+            distro = 'rolling' # fallback to rolling in default
+        system_role = constants.ROLE_SYSTEM_QUERY_DEFAULT.format(distro)
         user_messages = [
-            {"role": "system", "content": f"{constants.ROLE_SYSTEM_QUERY_DEFAULT}"},
+            {"role": "system", "content": f"{system_role}"},
             {"role": "user", "content": f"{sentence}"}
         ]