diff --git a/include/kabufuda/Card.hpp b/include/kabufuda/Card.hpp
index aac6ae9..6961508 100644
--- a/include/kabufuda/Card.hpp
+++ b/include/kabufuda/Card.hpp
@@ -157,7 +157,7 @@ public:
      * @param game
      * @param maker
      */
-    Card(const SystemString& filepath, const char* game = nullptr, const char* maker = nullptr);
+    Card(SystemStringView filepath, const char* game = nullptr, const char* maker = nullptr);
     ~Card();
 
     /**
@@ -409,7 +409,7 @@ public:
      * @brief Returns basic stats about a card image without opening a handle
      * @return ProbeResults structure
      */
-    static ProbeResults probeCardFile(const SystemString& filename);
+    static ProbeResults probeCardFile(SystemStringView filename);
 
     /**
      * @brief Writes any changes to the Card instance immediately to disk. <br />
@@ -425,7 +425,7 @@ public:
     /**
      * @brief Access host filename of card
      */
-    const SystemString& cardFilename() const { return m_filename; }
+    SystemStringView cardFilename() const { return m_filename; }
 
     /**
      * @brief Gets card-scope error state
diff --git a/include/kabufuda/Util.hpp b/include/kabufuda/Util.hpp
index 8cfeb1b..92d30f6 100644
--- a/include/kabufuda/Util.hpp
+++ b/include/kabufuda/Util.hpp
@@ -184,36 +184,31 @@ static inline double SBig(double val) { return val; }
 typedef wchar_t SystemChar;
 static inline size_t StrLen(const SystemChar* str) { return wcslen(str); }
 typedef std::wstring SystemString;
+typedef std::wstring_view SystemStringView;
 static inline void ToLower(SystemString& str) { std::transform(str.begin(), str.end(), str.begin(), towlower); }
 static inline void ToUpper(SystemString& str) { std::transform(str.begin(), str.end(), str.begin(), towupper); }
-class SystemUTF8View
+class SystemUTF8Conv
 {
     std::string m_utf8;
 
 public:
-    explicit SystemUTF8View(const SystemString& str) : m_utf8(WideToUTF8(str)) {}
-    operator const std::string&() const { return m_utf8; }
-    const std::string& str() const { return m_utf8; }
+    explicit SystemUTF8Conv(SystemStringView str) : m_utf8(WideToUTF8(str)) {}
+    std::string_view str() const { return m_utf8; }
     const char* c_str() const { return m_utf8.c_str(); }
-    std::string operator+(const std::string& other) const { return m_utf8 + other; }
-    std::string operator+(const char* other) const { return m_utf8 + other; }
+    std::string operator+(std::string_view other) const { return m_utf8 + other; }
 };
-inline std::string operator+(const std::string& lhs, const SystemUTF8View& rhs) { return lhs + std::string(rhs); }
-inline std::string operator+(const char* lhs, const SystemUTF8View& rhs) { return lhs + std::string(rhs); }
-class SystemStringView
+inline std::string operator+(std::string_view lhs, const SystemUTF8Conv& rhs) { return lhs + std::string(rhs); }
+class SystemStringConv
 {
     std::wstring m_sys;
 
 public:
-    explicit SystemStringView(const std::string& str) : m_sys(UTF8ToWide(str)) {}
-    operator const std::wstring&() const { return m_sys; }
-    const std::wstring& sys_str() const { return m_sys; }
+    explicit SystemStringConv(std::string_view str) : m_sys(UTF8ToWide(str)) {}
+    SystemStringView sys_str() const { return m_sys; }
     const SystemChar* c_str() const { return m_sys.c_str(); }
-    std::wstring operator+(const std::wstring& other) const { return m_sys + other; }
-    std::wstring operator+(const wchar_t* other) const { return m_sys + other; }
+    std::wstring operator+(const std::wstring_view other) const { return m_sys + other; }
 };
-inline std::wstring operator+(const std::wstring& lhs, const SystemStringView& rhs) { return lhs + std::wstring(rhs); }
-inline std::wstring operator+(const wchar_t* lhs, const SystemStringView& rhs) { return lhs + std::wstring(rhs); }
+inline std::wstring operator+(const std::wstring_view lhs, const SystemStringConv& rhs) { return lhs + std::wstring(rhs); }
 #ifndef _S
 #define _S(val) L##val
 #endif
@@ -222,36 +217,31 @@ typedef struct _stat Sstat;
 typedef char SystemChar;
 static inline size_t StrLen(const SystemChar* str) { return strlen(str); }
 typedef std::string SystemString;
+typedef std::string_view SystemStringView;
 static inline void ToLower(SystemString& str) { std::transform(str.begin(), str.end(), str.begin(), tolower); }
 static inline void ToUpper(SystemString& str) { std::transform(str.begin(), str.end(), str.begin(), toupper); }
-class SystemUTF8View
+class SystemUTF8Conv
 {
-    const std::string& m_utf8;
+    std::string_view m_utf8;
 
 public:
-    explicit SystemUTF8View(const SystemString& str) : m_utf8(str) {}
-    operator const std::string&() const { return m_utf8; }
-    const std::string& str() const { return m_utf8; }
-    const char* c_str() const { return m_utf8.c_str(); }
-    std::string operator+(const std::string& other) const { return std::string(m_utf8) + other; }
-    std::string operator+(const char* other) const { return std::string(m_utf8) + other; }
+    explicit SystemUTF8Conv(SystemStringView str) : m_utf8(str) {}
+    std::string_view str() const { return m_utf8; }
+    const char* c_str() const { return m_utf8.data(); }
+    std::string operator+(std::string_view other) const { return std::string(m_utf8) + other.data(); }
 };
-inline std::string operator+(const std::string& lhs, const SystemUTF8View& rhs) { return lhs + std::string(rhs); }
-inline std::string operator+(const char* lhs, const SystemUTF8View& rhs) { return lhs + std::string(rhs); }
-class SystemStringView
+inline std::string operator+(std::string_view lhs, const SystemUTF8Conv& rhs) { return std::string(lhs) + rhs.c_str(); }
+class SystemStringConv
 {
-    const std::string& m_sys;
+    SystemStringView m_sys;
 
 public:
-    explicit SystemStringView(const std::string& str) : m_sys(str) {}
-    operator const std::string&() const { return m_sys; }
-    const std::string& sys_str() const { return m_sys; }
-    const SystemChar* c_str() const { return m_sys.c_str(); }
-    std::string operator+(const std::string& other) const { return m_sys + other; }
-    std::string operator+(const char* other) const { return m_sys + other; }
+    explicit SystemStringConv(std::string_view str) : m_sys(str) {}
+    SystemStringView sys_str() const { return m_sys; }
+    const SystemChar* c_str() const { return m_sys.data(); }
+    std::string operator+(std::string_view other) const { return std::string(m_sys) + other.data(); }
 };
-inline std::string operator+(const std::string& lhs, const SystemStringView& rhs) { return lhs + std::string(rhs); }
-inline std::string operator+(const char* lhs, const SystemStringView& rhs) { return lhs + std::string(rhs); }
+inline std::string operator+(std::string_view lhs, const SystemStringConv& rhs) { return std::string(lhs) + rhs.c_str(); }
 #ifndef _S
 #define _S(val) val
 #endif
diff --git a/include/kabufuda/WideStringConvert.hpp b/include/kabufuda/WideStringConvert.hpp
index 44757a9..795fcc2 100644
--- a/include/kabufuda/WideStringConvert.hpp
+++ b/include/kabufuda/WideStringConvert.hpp
@@ -5,8 +5,8 @@
 
 namespace kabufuda
 {
-std::string WideToUTF8(const std::wstring& src);
-std::wstring UTF8ToWide(const std::string& src);
+std::string WideToUTF8(std::wstring_view src);
+std::wstring UTF8ToWide(std::string_view src);
 }
 
 #endif // __KABU_WIDESTRINGCONVERT_HPP__
diff --git a/lib/kabufuda/Card.cpp b/lib/kabufuda/Card.cpp
index abe0e94..13f7348 100644
--- a/lib/kabufuda/Card.cpp
+++ b/lib/kabufuda/Card.cpp
@@ -71,7 +71,7 @@ Card& Card::operator=(Card&& other)
     return *this;
 }
 
-Card::Card(const SystemString& filename, const char* game, const char* maker) : m_filename(filename)
+Card::Card(SystemStringView filename, const char* game, const char* maker) : m_filename(filename)
 {
     memset(__raw, 0xFF, BlockSize);
     if (game && strlen(game) == 4)
@@ -848,10 +848,10 @@ void Card::format(ECardSlot id, ECardSize size, EEncoding encoding)
     }
 }
 
-ProbeResults Card::probeCardFile(const SystemString& filename)
+ProbeResults Card::probeCardFile(SystemStringView filename)
 {
     Sstat stat;
-    if (Stat(filename.c_str(), &stat) || !S_ISREG(stat.st_mode))
+    if (Stat(filename.data(), &stat) || !S_ISREG(stat.st_mode))
         return { ECardResult::NOCARD, 0, 0 };
     return { ECardResult::READY, uint32_t(stat.st_size / BlockSize) / MbitToBlocks, 0x2000 };
 }
diff --git a/lib/kabufuda/WideStringConvert.cpp b/lib/kabufuda/WideStringConvert.cpp
index 50c8d86..7aca689 100644
--- a/lib/kabufuda/WideStringConvert.cpp
+++ b/lib/kabufuda/WideStringConvert.cpp
@@ -3,7 +3,7 @@
 
 namespace kabufuda
 {
-std::string WideToUTF8(const std::wstring& src)
+std::string WideToUTF8(std::wstring_view src)
 {
     std::string retval;
     retval.reserve(src.length());
@@ -21,11 +21,11 @@ std::string WideToUTF8(const std::wstring& src)
     return retval;
 }
 
-std::wstring UTF8ToWide(const std::string& src)
+std::wstring UTF8ToWide(std::string_view src)
 {
     std::wstring retval;
     retval.reserve(src.length());
-    const utf8proc_uint8_t* buf = reinterpret_cast<const utf8proc_uint8_t*>(src.c_str());
+    const utf8proc_uint8_t* buf = reinterpret_cast<const utf8proc_uint8_t*>(src.data());
     while (*buf)
     {
         utf8proc_int32_t wc;