diff --git a/internal/lightcone/harmony/pastselfinmirror/data.go b/internal/lightcone/harmony/pastselfinmirror/data.go
new file mode 100644
index 00000000..ac85ddeb
--- /dev/null
+++ b/internal/lightcone/harmony/pastselfinmirror/data.go
@@ -0,0 +1,71 @@
+// Code generated by "weapstat"; DO NOT EDIT.
+
+package pastselfinmirror
+
+import "github.com/simimpact/srsim/pkg/engine/equip/lightcone"
+
+var promotions = []lightcone.PromotionData{
+	{
+		MaxLevel: 20,
+		HPBase:   48,
+		HPAdd:    7.2,
+		ATKBase:  24,
+		ATKAdd:   3.6,
+		DEFBase:  24,
+		DEFAdd:   3.6,
+	},
+	{
+		MaxLevel: 30,
+		HPBase:   105.6,
+		HPAdd:    7.2,
+		ATKBase:  52.8,
+		ATKAdd:   3.6,
+		DEFBase:  52.8,
+		DEFAdd:   3.6,
+	},
+	{
+		MaxLevel: 40,
+		HPBase:   182.4,
+		HPAdd:    7.2,
+		ATKBase:  91.2,
+		ATKAdd:   3.6,
+		DEFBase:  91.2,
+		DEFAdd:   3.6,
+	},
+	{
+		MaxLevel: 50,
+		HPBase:   259.2,
+		HPAdd:    7.2,
+		ATKBase:  129.6,
+		ATKAdd:   3.6,
+		DEFBase:  129.6,
+		DEFAdd:   3.6,
+	},
+	{
+		MaxLevel: 60,
+		HPBase:   336,
+		HPAdd:    7.2,
+		ATKBase:  168,
+		ATKAdd:   3.6,
+		DEFBase:  168,
+		DEFAdd:   3.6,
+	},
+	{
+		MaxLevel: 70,
+		HPBase:   412.8,
+		HPAdd:    7.2,
+		ATKBase:  206.4,
+		ATKAdd:   3.6,
+		DEFBase:  206.4,
+		DEFAdd:   3.6,
+	},
+	{
+		MaxLevel: 80,
+		HPBase:   489.6,
+		HPAdd:    7.2,
+		ATKBase:  244.8,
+		ATKAdd:   3.6,
+		DEFBase:  244.8,
+		DEFAdd:   3.6,
+	},
+}
\ No newline at end of file
diff --git a/internal/lightcone/harmony/pastselfinmirror/pastselfinmirror.go b/internal/lightcone/harmony/pastselfinmirror/pastselfinmirror.go
new file mode 100644
index 00000000..bfd335b1
--- /dev/null
+++ b/internal/lightcone/harmony/pastselfinmirror/pastselfinmirror.go
@@ -0,0 +1,86 @@
+package pastselfinmirror
+
+import (
+	"github.com/simimpact/srsim/pkg/engine"
+	"github.com/simimpact/srsim/pkg/engine/equip/lightcone"
+	"github.com/simimpact/srsim/pkg/engine/event"
+	"github.com/simimpact/srsim/pkg/engine/info"
+	"github.com/simimpact/srsim/pkg/engine/modifier"
+	"github.com/simimpact/srsim/pkg/engine/prop"
+	"github.com/simimpact/srsim/pkg/key"
+	"github.com/simimpact/srsim/pkg/model"
+)
+
+const (
+	psim       = "past-self-in-mirror"
+	psimEnergy = "past-self-in-mirror-energy"
+)
+
+// Increases the wearer's Break Effect by 60%.
+// When the wearer uses their Ultimate, increases all allies' DMG by 24%, lasting for 3 turn(s).
+// Should the wearer's Break Effect exceed or equal 150%, 1 Skill Point will be recovered.
+// At the start of each wave, all allies regenerate 10 Energy immediately. Abilities of the same type cannot stack.
+func init() {
+	lightcone.Register(key.PastSelfinMirror, lightcone.Config{
+		CreatePassive: Create,
+		Rarity:        5,
+		Path:          model.Path_HARMONY,
+		Promotions:    promotions,
+	})
+	modifier.Register(psim, modifier.Config{
+		Stacking:   modifier.ReplaceBySource,
+		StatusType: model.StatusType_STATUS_BUFF,
+		Listeners: modifier.Listeners{
+			OnAfterAction: afterUlt,
+		},
+	})
+}
+
+// Break Effect Buff
+func Create(engine engine.Engine, owner key.TargetID, lc info.LightCone) {
+	amt := 0.5 + 0.1*float64(lc.Imposition)
+	engine.AddModifier(owner, info.Modifier{
+		Name:   psim,
+		Source: owner,
+		Stats:  info.PropMap{prop.BreakEffect: amt},
+		State:  float64(lc.Imposition),
+	})
+
+	energyAmt := 7.5 + 2.5*float64(lc.Imposition)
+	engine.Events().BattleStart.Subscribe(func(event event.BattleStart) {
+		for _, char := range engine.Characters() {
+			engine.ModifyEnergy(info.ModifyAttribute{
+				Key:    psimEnergy,
+				Target: char,
+				Source: owner,
+				Amount: energyAmt,
+			})
+		}
+	})
+}
+
+func afterUlt(mod *modifier.Instance, e event.ActionEnd) {
+	if e.AttackType != model.AttackType_ULT {
+		return
+	}
+
+	// Restore 1 SP if BE >= 150%
+	if mod.OwnerStats().BreakEffect() >= 1.5 {
+		mod.Engine().ModifySP(info.ModifySP{
+			Key:    psim,
+			Source: mod.Owner(),
+			Amount: 1,
+		})
+	}
+
+	// DMG% buff for 3 turns
+	amt := 0.2 + 0.04*mod.State().(float64)
+	for _, char := range mod.Engine().Characters() {
+		mod.Engine().AddModifier(char, info.Modifier{
+			Name:     psim,
+			Source:   mod.Owner(),
+			Stats:    info.PropMap{prop.AllDamagePercent: amt},
+			Duration: 3,
+		})
+	}
+}
diff --git a/pkg/key/lightcone.go b/pkg/key/lightcone.go
index a2a912c6..96a8381a 100644
--- a/pkg/key/lightcone.go
+++ b/pkg/key/lightcone.go
@@ -71,6 +71,7 @@ const (
 	MemoriesofthePast          LightCone = "memories_of_the_past"
 	DanceDanceDance            LightCone = "dance_dance_dance"
 	PlanetaryRendezvous        LightCone = "planetary_rendezvous"
+	PastSelfinMirror           LightCone = "past_self_in_mirror"
 )
 
 // Preservation
diff --git a/pkg/simulation/imports.go b/pkg/simulation/imports.go
index 4a851c79..29c24577 100644
--- a/pkg/simulation/imports.go
+++ b/pkg/simulation/imports.go
@@ -66,6 +66,7 @@ import (
 	_ "github.com/simimpact/srsim/internal/lightcone/harmony/dancedancedance"
 	_ "github.com/simimpact/srsim/internal/lightcone/harmony/memoriesofthepast"
 	_ "github.com/simimpact/srsim/internal/lightcone/harmony/meshingcogs"
+	_ "github.com/simimpact/srsim/internal/lightcone/harmony/pastselfinmirror"
 	_ "github.com/simimpact/srsim/internal/lightcone/harmony/planetaryrendezvous"
 	_ "github.com/simimpact/srsim/internal/lightcone/hunt/adversarial"
 	_ "github.com/simimpact/srsim/internal/lightcone/hunt/arrows"