String response = "Night_Time";
String Time     = "          ";

void setup() {
  Serial.begin(115200);
  Serial.println("Setup-Start");
  int i, flag;
  for (i = 0; i < response.length(); i++) {
    Serial.print("response[");
    Serial.print(i);
    Serial.print("]=#");
    Serial.print(response[i]);
    Serial.println("#");

    if (response[i] == '_') {
      Serial.println("found the _");
      flag = 1;
    }

    if (flag == 1) {
      Time[i] = response[i];
      Serial.print("Time[");
      Serial.print(i);
      Serial.print("]=#");
      Serial.print(Time[i]);
      Serial.println("#");
    }
  }
}

void loop() {
  // put your main code here, to run repeatedly:

}