diff --git a/src/main/java/com/github/sttk/sabi/DataHub.java b/src/main/java/com/github/sttk/sabi/DataHub.java
index d817061..291384d 100644
--- a/src/main/java/com/github/sttk/sabi/DataHub.java
+++ b/src/main/java/com/github/sttk/sabi/DataHub.java
@@ -94,6 +94,14 @@ public record FailToCastDataConn(String name, String castToType) {}
    */
   public record RuntimeExceptionOccurred() {}
 
+  /**
+   * Represents an error reason that occurred when failing to cast the {@code DataHub} instance
+   * itself to the expected data access interface type for a {@link Logic}.
+   *
+   * @param castFromType The actual type of the {@code DataHub} instance that failed to cast.
+   */
+  public record FailToCastDataHub(String castFromType) {}
+
   private final DataHubInner inner = new DataHubInner();
 
   /** Constructs a new {@code DataHub} instance. */
@@ -161,4 +169,68 @@ void rollback() {
   void end() {
     inner.end();
   }
+
+  /**
+   * Executes the provided application {@link Logic} without transactional boundaries. The {@code
+   * DataHub} instance is treated as the data access object {@code D} to the {@link Logic}'s {@code
+   * run} method.
+   *
+   * @param <D> The type of the data access object, which typically is {@code DataHub} or an
+   *     interface implemented by {@code DataHub} that {@link Logic} expects.
+   * @param logic The application logic to execute.
+   * @throws Err if an {@link Err} or {@link RuntimeException} occurs during logic execution or if
+   *     the {@code DataHub} cannot be cast to the expected data access type.
+   */
+  public <D> void run(Logic<D> logic) throws Err {
+    D data;
+    try {
+      @SuppressWarnings("unchecked")
+      D d = (D) this;
+      data = d;
+    } catch (Exception e) {
+      throw new Err(new FailToCastDataHub(this.getClass().getName()));
+    }
+    try {
+      this.begin();
+      logic.run(data);
+    } catch (Err | RuntimeException e) {
+      throw e;
+    } finally {
+      this.end();
+    }
+  }
+
+  /**
+   * Executes the provided application {@link Logic} within a transactional context. The {@code
+   * DataHub} instance is treated as the data access object {@code D} to the {@link Logic}'s {@code
+   * run} method. If the logic completes successfully, a commit operation is attempted. If any
+   * {@link Err}, {@link RuntimeException}, or {@link Error} occurs, a rollback operation is
+   * performed.
+   *
+   * @param <D> The type of the data access object, which typically is {@code DataHub} or an
+   *     interface implemented by {@code DataHub} that {@link Logic} expects.
+   * @param logic The application logic to execute transactionally.
+   * @throws Err if an {@link Err}, {@link RuntimeException}, or {@link Error} occurs during logic
+   *     execution, pre-commit, or commit. The original exception is re-thrown after rollback.
+   */
+  public <D> void txn(Logic<D> logic) throws Err {
+    D data;
+    try {
+      @SuppressWarnings("unchecked")
+      D d = (D) this;
+      data = d;
+    } catch (Exception e) {
+      throw new Err(new FailToCastDataHub(this.getClass().getName()));
+    }
+    try {
+      this.begin();
+      logic.run(data);
+      this.commit();
+    } catch (Err | RuntimeException | Error e) {
+      this.rollback();
+      throw e;
+    } finally {
+      this.end();
+    }
+  }
 }
diff --git a/src/main/java/com/github/sttk/sabi/Sabi.java b/src/main/java/com/github/sttk/sabi/Sabi.java
index 796bf07..17bd782 100644
--- a/src/main/java/com/github/sttk/sabi/Sabi.java
+++ b/src/main/java/com/github/sttk/sabi/Sabi.java
@@ -34,14 +34,6 @@
  *   }</code></pre>
  */
 public final class Sabi {
-  /**
-   * Represents an error reason that occurred when failing to cast the {@code DataHub} instance
-   * itself to the expected data access interface type for a {@link Logic}.
-   *
-   * @param castFromType The actual type of the {@code DataHub} instance that failed to cast.
-   */
-  public record FailToCastDataHub(String castFromType) {}
-
   private Sabi() {}
 
   /**
@@ -71,72 +63,4 @@ public static void uses(String name, DataSrc ds) {
   public static AutoCloseable setup() throws Err {
     return DataHubInner.setupGlobals();
   }
-
-  /**
-   * Executes the provided application {@link Logic} without transactional boundaries. The {@code
-   * DataHub} instance in the parameters is passed as the data access object {@code D} to the {@link
-   * Logic}'s {@code run} method.
-   *
-   * @param <D> The type of the data access object, which typically is {@code DataHub} or an
-   *     interface implemented by {@code DataHub} that {@link Logic} expects.
-   * @param logic The application logic to execute.
-   * @param hub An instance of a DataHub subclass that inherits the data interface for logic
-   *     arguments.
-   * @throws Err if an {@link Err} or {@link RuntimeException} occurs during logic execution or if
-   *     the {@code DataHub} cannot be cast to the expected data access type.
-   */
-  public static <D> void run(Logic<D> logic, DataHub hub) throws Err {
-    D data;
-    try {
-      @SuppressWarnings("unchecked")
-      D d = (D) hub;
-      data = d;
-    } catch (Exception e) {
-      throw new Err(new FailToCastDataHub(hub.getClass().getName()));
-    }
-    try {
-      hub.begin();
-      logic.run(data);
-    } catch (Err | RuntimeException e) {
-      throw e;
-    } finally {
-      hub.end();
-    }
-  }
-
-  /**
-   * Executes the provided application {@link Logic} within a transactional context. The {@code
-   * DataHub} instance in the parameter is passed as the data access object {@code D} to the {@link
-   * Logic}'s {@code run} method. If the logic completes successfully, a commit operation is
-   * attempted. If any {@link Err}, {@link RuntimeException}, or {@link Error} occurs, a rollback
-   * operation is performed.
-   *
-   * @param <D> The type of the data access object, which typically is {@code DataHub} or an
-   *     interface implemented by {@code DataHub} that {@link Logic} expects.
-   * @param logic The application logic to execute transactionally.
-   * @param hub An instance of a DataHub subclass that inherits the data interface for logic
-   *     arguments.
-   * @throws Err if an {@link Err}, {@link RuntimeException}, or {@link Error} occurs during logic
-   *     execution, pre-commit, or commit. The original exception is re-thrown after rollback.
-   */
-  public static <D> void txn(Logic<D> logic, DataHub hub) throws Err {
-    D data;
-    try {
-      @SuppressWarnings("unchecked")
-      D d = (D) hub;
-      data = d;
-    } catch (Exception e) {
-      throw new Err(new FailToCastDataHub(hub.getClass().getName()));
-    }
-    try {
-      hub.begin();
-      logic.run(data);
-      hub.commit();
-    } catch (Err | RuntimeException | Error e) {
-      hub.rollback();
-      throw e;
-    } finally {
-      hub.end();
-    }
-  }
 }
diff --git a/src/test/java/com/github/sttk/sabi/internal/DataAccTest.java b/src/test/java/com/github/sttk/sabi/internal/DataAccTest.java
index 771d881..a269a94 100644
--- a/src/test/java/com/github/sttk/sabi/internal/DataAccTest.java
+++ b/src/test/java/com/github/sttk/sabi/internal/DataAccTest.java
@@ -317,7 +317,7 @@ void test() {
       try (var ac = Sabi.setup()) {
         suppressWarnings_unused(ac);
         try (var data = new SampleDataHub()) {
-          Sabi.run(new SampleLogic(), data);
+          data.run(new SampleLogic());
         } catch (Exception e) {
           fail(e);
         }
@@ -362,7 +362,7 @@ void test() {
           data.uses("foo", new FooDataSrc(1, "hello", logger, false));
           data.uses("bar", new BarDataSrc(2, logger, false));
 
-          Sabi.run(new SampleLogic(), data);
+          data.run(new SampleLogic());
         } catch (Exception e) {
           fail(e);
         }
@@ -394,7 +394,7 @@ void test_not_run_logic_if_fail_to_setup_local_data_src() {
           data.uses("foo", new FooDataSrc(1, "hello", logger, true));
           data.uses("bar", new BarDataSrc(2, logger, false));
 
-          Sabi.run(new SampleLogic(), data);
+          data.run(new SampleLogic());
         } catch (Err e) {
           switch (e.getReason()) {
             case DataHub.FailToSetupLocalDataSrcs r -> {
@@ -437,7 +437,7 @@ void test() {
         try (var data = new SampleDataHub()) {
           data.uses("foo", new FooDataSrc(2, "Hello", logger, false));
 
-          Sabi.run(new SampleLogic(), data);
+          data.run(new SampleLogic());
         } catch (Exception e) {
           fail(e);
         }
@@ -482,7 +482,7 @@ void test() {
       try (var ac = Sabi.setup()) {
         suppressWarnings_unused(ac);
         try (var data = new SampleDataHub()) {
-          Sabi.txn(new SampleLogic(), data);
+          data.txn(new SampleLogic());
         } catch (Exception e) {
           fail(e);
         }
@@ -533,7 +533,7 @@ void test() {
           data.uses("foo", new FooDataSrc(1, "Hello", logger, false));
           data.uses("bar", new BarDataSrc(2, logger, false));
 
-          Sabi.txn(new SampleLogic(), data);
+          data.txn(new SampleLogic());
         } catch (Exception e) {
           fail(e);
         }
@@ -571,7 +571,7 @@ void test_not_run_logic_if_fail_to_setup_local_data_src() {
           data.uses("foo", new FooDataSrc(1, "Hello", logger, true));
           data.uses("bar", new BarDataSrc(2, logger, false));
 
-          Sabi.txn(new SampleLogic(), data);
+          data.txn(new SampleLogic());
         } catch (Err e) {
           switch (e.getReason()) {
             case DataHub.FailToSetupLocalDataSrcs r -> {
@@ -600,7 +600,7 @@ void test_not_run_logic_in_txn_and_rollback() {
           data.uses("foo", new FooDataSrc(1, "Hello", logger, false));
           data.uses("bar", new BarDataSrc(2, logger, false));
 
-          Sabi.txn(new FailingLogic(), data);
+          data.txn(new FailingLogic());
         } catch (Err e) {
           assertThat(e.getReason()).isEqualTo("ZZZ");
         } catch (Exception e) {
@@ -643,7 +643,7 @@ void test() {
         try (var data = new SampleDataHub()) {
           data.uses("foo", new FooDataSrc(2, "Hello", logger, false));
 
-          Sabi.txn(new SampleLogic(), data);
+          data.txn(new SampleLogic());
         } catch (Exception e) {
           fail(e);
         }