diff --git a/feature/floor-map/src/main/java/io/github/droidkaigi/confsched2023/floormap/FloorMapScreenViewModel.kt b/feature/floor-map/src/main/java/io/github/droidkaigi/confsched2023/floormap/FloorMapScreenViewModel.kt
index 84095c0c0..fefb17ed7 100644
--- a/feature/floor-map/src/main/java/io/github/droidkaigi/confsched2023/floormap/FloorMapScreenViewModel.kt
+++ b/feature/floor-map/src/main/java/io/github/droidkaigi/confsched2023/floormap/FloorMapScreenViewModel.kt
@@ -6,19 +6,30 @@ import io.github.droidkaigi.confsched2023.floormap.FloorMapContentUiState.LargeF
 import io.github.droidkaigi.confsched2023.floormap.FloorMapContentUiState.SmallFloorMapContentUiState
 import io.github.droidkaigi.confsched2023.floormap.section.FloorMapSideEventListUiState
 import io.github.droidkaigi.confsched2023.floormap.section.FloorMapUiState
+import io.github.droidkaigi.confsched2023.model.DroidKaigi2023Day.Day3
 import io.github.droidkaigi.confsched2023.model.FloorLevel
 import io.github.droidkaigi.confsched2023.model.SideEvents
 import io.github.droidkaigi.confsched2023.ui.UserMessageStateHolder
 import io.github.droidkaigi.confsched2023.ui.buildUiState
 import kotlinx.collections.immutable.toImmutableList
 import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.datetime.Clock
+import kotlinx.datetime.TimeZone
+import kotlinx.datetime.toInstant
+import kotlinx.datetime.toLocalDateTime
 import javax.inject.Inject
 
 @HiltViewModel
 class FloorMapScreenViewModel @Inject constructor(
     val userMessageStateHolder: UserMessageStateHolder,
 ) : ViewModel(), UserMessageStateHolder by userMessageStateHolder {
-    private val floorLevelStateFlow = MutableStateFlow(FloorLevel.Basement)
+    private val floorLevelStateFlow = MutableStateFlow(
+        if (isTodayDay3()) {
+            FloorLevel.Ground
+        } else {
+            FloorLevel.Basement
+        },
+    )
     private val floorMapSideEventListUiState = FloorMapSideEventListUiState(
         sideEvents = SideEvents,
     )
@@ -57,6 +68,15 @@ class FloorMapScreenViewModel @Inject constructor(
         )
     }
 
+    private fun isTodayDay3(): Boolean {
+        val now = Clock.System.now().toLocalDateTime(TimeZone.currentSystemDefault())
+
+        val currentInTokyo = now.toInstant(TimeZone.currentSystemDefault()).toLocalDateTime(
+            TimeZone.of("Asia/Tokyo"),
+        )
+        return currentInTokyo >= Day3.start.toLocalDateTime(TimeZone.of("Asia/Tokyo")) &&
+            currentInTokyo < Day3.end.toLocalDateTime(TimeZone.of("Asia/Tokyo"))
+    }
     fun onClickFloorLevelSwitcher(floorLevel: FloorLevel) {
         floorLevelStateFlow.value = floorLevel
     }