diff --git a/src/sys/nact.h b/src/sys/nact.h
index 00a204b..75d4c4f 100644
--- a/src/sys/nact.h
+++ b/src/sys/nact.h
@@ -198,7 +198,6 @@ protected:
 
 	// 下位関数
 	virtual uint16 cali() = 0;
-	virtual uint16 cali2() = 0;
 	bool is_message(uint8_t c) { return c == ' ' || c & 0x80; }
 
 	uint16 random(uint16 range);
@@ -293,7 +292,7 @@ protected:
 	void cmd_z() override;
 	void opening() override;
 	uint16 cali() override;
-	uint16 cali2() override;
+
 private:
 	// Intruder Zコマンド
 	int paint_x;
@@ -339,7 +338,6 @@ protected:
 	void cmd_y() override;
 	void cmd_z() override;
 	uint16 cali() override;
-	uint16 cali2() override;
 };
 
 class NACT_Sys3 final : public NACT {
@@ -380,8 +378,10 @@ protected:
 	void cmd_y() override;
 	void cmd_z() override;
 	uint16 cali() override;
-	uint16 cali2() override;
+
 private:
+	uint16 cali2();
+
 	struct K3HackInfo;
 	static const K3HackInfo yakata3cd_k3_hack_table[];
 	static const K3HackInfo yakata3fd_k3_hack_table[];
diff --git a/src/sys/nact_sys1.cpp b/src/sys/nact_sys1.cpp
index 9e93257..fb7ded3 100644
--- a/src/sys/nact_sys1.cpp
+++ b/src/sys/nact_sys1.cpp
@@ -1297,21 +1297,3 @@ uint16 NACT_Sys1::cali()
 	}
 	return (uint16)(cali[1] & 0xffff);
 }
-
-uint16 NACT_Sys1::cali2()
-{
-	uint16 val = 0;
-	uint16 dat = sco.getd();
-
-	if(0x80 <= dat && dat <= 0xbf) {
-		val = dat & 0x3f;
-	} else if(0xc0 <= dat && dat <= 0xff) {
-		val = ((dat & 0x3f) << 8) | sco.getd();
-	} else {
-		sys_error("cali2: invalid expression at %d:%04x", sco.page(), sco.cmd_addr());
-	}
-	if (sco.getd() != 0x7f) {
-		sys_error("cali2: invalid expression at %d:%04x", sco.page(), sco.cmd_addr());
-	}
-	return val;
-}
diff --git a/src/sys/nact_sys2.cpp b/src/sys/nact_sys2.cpp
index 48f8854..d8815b5 100644
--- a/src/sys/nact_sys2.cpp
+++ b/src/sys/nact_sys2.cpp
@@ -1266,21 +1266,3 @@ uint16 NACT_Sys2::cali()
 	}
 	return (uint16)(cali[1] & 0xffff);
 }
-
-uint16 NACT_Sys2::cali2()
-{
-	uint16 val = 0;
-	uint16 dat = sco.getd();
-
-	if(0x80 <= dat && dat <= 0xbf) {
-		val = dat & 0x3f;
-	} else if(0xc0 <= dat && dat <= 0xff) {
-		val = ((dat & 0x3f) << 8) | sco.getd();
-	} else {
-		sys_error("cali2: invalid expression at %d:%04x", sco.page(), sco.cmd_addr());
-	}
-	if (sco.getd() != 0x7f) {
-		sys_error("cali2: invalid expression at %d:%04x", sco.page(), sco.cmd_addr());
-	}
-	return val;
-}