diff --git a/app/database/migrations/2026_10_11_000001_create_users_table.php b/app/database/migrations/2026_10_11_000001_create_users_table.php
new file mode 100644
index 0000000..37ec582
--- /dev/null
+++ b/app/database/migrations/2026_10_11_000001_create_users_table.php
@@ -0,0 +1,26 @@
+<?php
+
+declare(strict_types=1);
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration {
+    public function up(): void {
+        Schema::create('users', function (Blueprint $table): void {
+            $table->increments('user_id');
+            $table->string('email', 255);
+            $table->string('password_hash', 255);
+            $table->string('name', 255);
+            $table->timestamp('created_datetime')->useCurrent();
+            $table->timestamp('updated_datetime')->nullable();
+
+            $table->unique('email', 'idx_email');
+        });
+    }
+
+    public function down(): void {
+        Schema::dropIfExists('users');
+    }
+};
diff --git a/app/database/migrations/2026_10_11_000002_create_boards_table.php b/app/database/migrations/2026_10_11_000002_create_boards_table.php
new file mode 100644
index 0000000..6fd3e90
--- /dev/null
+++ b/app/database/migrations/2026_10_11_000002_create_boards_table.php
@@ -0,0 +1,29 @@
+<?php
+
+declare(strict_types=1);
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration {
+    public function up(): void {
+        Schema::create('boards', function (Blueprint $table): void {
+            $table->increments('board_id');
+            $table->string('title', 255);
+            $table->integer('owner_user_id');
+            $table->boolean('is_public')->default(false);
+            $table->timestamp('created_datetime')->useCurrent();
+            $table->timestamp('updated_datetime')->nullable();
+
+            $table->foreign('owner_user_id')
+                ->references('user_id')
+                ->on('users')
+                ->onDelete('cascade');
+        });
+    }
+
+    public function down(): void {
+        Schema::dropIfExists('boards');
+    }
+};
diff --git a/app/database/migrations/2026_10_11_000003_create_board_columns_table.php b/app/database/migrations/2026_10_11_000003_create_board_columns_table.php
new file mode 100644
index 0000000..6351171
--- /dev/null
+++ b/app/database/migrations/2026_10_11_000003_create_board_columns_table.php
@@ -0,0 +1,30 @@
+<?php
+
+declare(strict_types=1);
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration {
+    public function up(): void {
+        Schema::create('board_columns', function (Blueprint $table): void {
+            $table->increments('column_id');
+            $table->integer('board_id');
+            $table->smallInteger('ordinal_position');
+            $table->string('title', 255);
+            $table->string('color', 6)->nullable();
+
+            $table->index('board_id', 'idx_board_id');
+
+            $table->foreign('board_id')
+                ->references('board_id')
+                ->on('boards')
+                ->onDelete('cascade');
+        });
+    }
+
+    public function down(): void {
+        Schema::dropIfExists('board_columns');
+    }
+};
diff --git a/app/database/migrations/2026_10_11_000004_create_cards_table.php b/app/database/migrations/2026_10_11_000004_create_cards_table.php
new file mode 100644
index 0000000..ad82ea7
--- /dev/null
+++ b/app/database/migrations/2026_10_11_000004_create_cards_table.php
@@ -0,0 +1,41 @@
+<?php
+
+declare(strict_types=1);
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\DB;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration {
+    public function up(): void {
+        Schema::create('cards', function (Blueprint $table): void {
+            $table->increments('card_id');
+            $table->integer('board_id');
+            $table->integer('column_id');
+            $table->smallInteger('sort_index');
+            $table->string('title', 255);
+            $table->text('content')->nullable();
+            $table->string('color', 6)->nullable();
+            $table->boolean('is_archived')->default(false);
+            $table->timestamp('created_datetime')->useCurrent();
+            $table->timestamp('updated_datetime')->nullable();
+
+            $table->foreign('board_id')
+                ->references('board_id')
+                ->on('boards')
+                ->onDelete('cascade');
+
+            $table->foreign('column_id')
+                ->references('column_id')
+                ->on('board_columns')
+                ->onDelete('cascade');
+        });
+
+        DB::statement('create index "idx_active_board_id" on "cards" ("board_id") where "is_archived" = false');
+    }
+
+    public function down(): void {
+        Schema::dropIfExists('cards');
+    }
+};
diff --git a/app/src/Models/Board.php b/app/src/Models/Board.php
new file mode 100644
index 0000000..4965cc4
--- /dev/null
+++ b/app/src/Models/Board.php
@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+use Illuminate\Database\Eloquent\Relations\HasMany;
+
+final class Board extends Model {
+    protected $table = 'boards';
+
+    protected $primaryKey = 'board_id';
+
+    public $timestamps = false;
+
+    protected $fillable = ['title', 'owner_user_id', 'is_public'];
+
+    protected $casts = [
+        'board_id'         => 'int',
+        'owner_user_id'    => 'int',
+        'is_public'        => 'bool',
+        'created_datetime' => 'datetime',
+        'updated_datetime' => 'datetime',
+    ];
+
+    public function owner(): BelongsTo {
+        return $this->belongsTo(User::class, 'owner_user_id', 'user_id');
+    }
+
+    public function columns(): HasMany {
+        return $this->hasMany(BoardColumn::class, 'board_id', 'board_id');
+    }
+
+    public function cards(): HasMany {
+        return $this->hasMany(Card::class, 'board_id', 'board_id');
+    }
+}
diff --git a/app/src/Models/BoardColumn.php b/app/src/Models/BoardColumn.php
new file mode 100644
index 0000000..7c2e469
--- /dev/null
+++ b/app/src/Models/BoardColumn.php
@@ -0,0 +1,33 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+use Illuminate\Database\Eloquent\Relations\HasMany;
+
+final class BoardColumn extends Model {
+    protected $table = 'board_columns';
+
+    protected $primaryKey = 'column_id';
+
+    public $timestamps = false;
+
+    protected $fillable = ['board_id', 'ordinal_position', 'title', 'color'];
+
+    protected $casts = [
+        'column_id'        => 'int',
+        'board_id'         => 'int',
+        'ordinal_position' => 'int',
+    ];
+
+    public function board(): BelongsTo {
+        return $this->belongsTo(Board::class, 'board_id', 'board_id');
+    }
+
+    public function cards(): HasMany {
+        return $this->hasMany(Card::class, 'column_id', 'column_id');
+    }
+}
diff --git a/app/src/Models/Card.php b/app/src/Models/Card.php
new file mode 100644
index 0000000..e90a46c
--- /dev/null
+++ b/app/src/Models/Card.php
@@ -0,0 +1,36 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+
+final class Card extends Model {
+    protected $table = 'cards';
+
+    protected $primaryKey = 'card_id';
+
+    public $timestamps = false;
+
+    protected $fillable = ['board_id', 'column_id', 'sort_index', 'title', 'content', 'color', 'is_archived'];
+
+    protected $casts = [
+        'card_id'          => 'int',
+        'board_id'         => 'int',
+        'column_id'        => 'int',
+        'sort_index'       => 'int',
+        'is_archived'      => 'bool',
+        'created_datetime' => 'datetime',
+        'updated_datetime' => 'datetime',
+    ];
+
+    public function board(): BelongsTo {
+        return $this->belongsTo(Board::class, 'board_id', 'board_id');
+    }
+
+    public function column(): BelongsTo {
+        return $this->belongsTo(BoardColumn::class, 'column_id', 'column_id');
+    }
+}
diff --git a/app/src/Models/User.php b/app/src/Models/User.php
new file mode 100644
index 0000000..c7502d8
--- /dev/null
+++ b/app/src/Models/User.php
@@ -0,0 +1,30 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\HasMany;
+
+final class User extends Model {
+    protected $table = 'users';
+
+    protected $primaryKey = 'user_id';
+
+    public $timestamps = false;
+
+    protected $fillable = ['email', 'password_hash', 'name'];
+
+    protected $hidden = ['password_hash'];
+
+    protected $casts = [
+        'user_id'          => 'int',
+        'created_datetime' => 'datetime',
+        'updated_datetime' => 'datetime',
+    ];
+
+    public function boards(): HasMany {
+        return $this->hasMany(Board::class, 'owner_user_id', 'user_id');
+    }
+}