diff --git a/spec b/spec
index 7aab83ed8b..dd160ae094 100644
--- a/spec
+++ b/spec
@@ -2108,8 +2108,7 @@ beginseg
     name "ovl_Obj_Boyo"
     compress
     include "build/src/overlays/actors/ovl_Obj_Boyo/z_obj_boyo.o"
-    include "build/data/ovl_Obj_Boyo/ovl_Obj_Boyo.data.o"
-    include "build/data/ovl_Obj_Boyo/ovl_Obj_Boyo.reloc.o"
+    include "build/src/overlays/actors/ovl_Obj_Boyo/ovl_Obj_Boyo_reloc.o"
 endseg
 
 beginseg
diff --git a/src/overlays/actors/ovl_Obj_Boyo/z_obj_boyo.c b/src/overlays/actors/ovl_Obj_Boyo/z_obj_boyo.c
index e5e53000a7..9e791f7ae9 100644
--- a/src/overlays/actors/ovl_Obj_Boyo/z_obj_boyo.c
+++ b/src/overlays/actors/ovl_Obj_Boyo/z_obj_boyo.c
@@ -1,4 +1,7 @@
 #include "z_obj_boyo.h"
+#include "overlays/actors/ovl_En_Kaizoku/z_en_kaizoku.h"
+#include "overlays/actors/ovl_En_Bom/z_en_bom.h"
+#include "objects/object_boyo/object_boyo.h"
 
 #define FLAGS (ACTOR_FLAG_10)
 
@@ -9,7 +12,11 @@ void ObjBoyo_Destroy(Actor* thisx, PlayState* play2);
 void ObjBoyo_Update(Actor* thisx, PlayState* play2);
 void ObjBoyo_Draw(Actor* thisx, PlayState* play);
 
-/*
+void ObjBoyo_PushPlayer(ObjBoyo* this, Actor* actor);
+void ObjBoyo_PushPirate(ObjBoyo* this, Actor* actor);
+void ObjBoyo_ExplodeBomb(ObjBoyo* this, Actor* actor);
+Actor* ObjBoyo_FindCollidedActor(ObjBoyo* this, PlayState* play, s32* index);
+
 const ActorInit Obj_Boyo_InitVars = {
     ACTOR_OBJ_BOYO,
     ACTORCAT_PROP,
@@ -19,22 +26,184 @@ const ActorInit Obj_Boyo_InitVars = {
     (ActorFunc)ObjBoyo_Init,
     (ActorFunc)ObjBoyo_Destroy,
     (ActorFunc)ObjBoyo_Update,
-    (ActorFunc)ObjBoyo_Draw
+    (ActorFunc)ObjBoyo_Draw,
 };
-*/
 
-#pragma GLOBAL_ASM("asm/non_matchings/overlays/ovl_Obj_Boyo/ObjBoyo_Init.s")
+typedef void (*ObjBoyoCollisionHandler)(ObjBoyo* this, Actor* actor);
 
-#pragma GLOBAL_ASM("asm/non_matchings/overlays/ovl_Obj_Boyo/ObjBoyo_Destroy.s")
+typedef struct ObjBoyoUnkStruct {
+    /* 0x0 */ s16 id;
+    /* 0x4 */ ObjBoyoCollisionHandler colHandler;
+} ObjBoyoUnkStruct; // size = 0x8
 
-#pragma GLOBAL_ASM("asm/non_matchings/overlays/ovl_Obj_Boyo/func_809A5DC0.s")
+static ColliderCylinderInit sCylinderInit = {
+    {
+        COLTYPE_NONE,
+        AT_NONE,
+        AC_TYPE_PLAYER | AC_HARD | AC_ON,
+        OC1_TYPE_2 | OC1_TYPE_1 | OC1_TYPE_PLAYER | OC1_ON,
+        OC2_TYPE_2,
+        COLSHAPE_CYLINDER,
+    },
+    {
+        ELEMTYPE_UNK0,
+        { 0x00000000, 0x00, 0x00 },
+        { 0x01CBFFBE, 0x00, 0x00 },
+        TOUCH_NONE,
+        BUMP_ON,
+        OCELEM_ON,
+    },
+    {
+        60,
+        140,
+        0,
+        { 0, 0, 0 },
+    },
+};
 
-#pragma GLOBAL_ASM("asm/non_matchings/overlays/ovl_Obj_Boyo/func_809A5DE0.s")
+static InitChainEntry sInitChain[] = {
+    ICHAIN_F32(uncullZoneForward, 4000, ICHAIN_CONTINUE),
+    ICHAIN_F32(uncullZoneScale, 300, ICHAIN_CONTINUE),
+    ICHAIN_F32(uncullZoneDownward, 300, ICHAIN_CONTINUE),
+    ICHAIN_VEC3F_DIV1000(scale, 100, ICHAIN_STOP),
+};
 
-#pragma GLOBAL_ASM("asm/non_matchings/overlays/ovl_Obj_Boyo/func_809A5E14.s")
+static ObjBoyoUnkStruct sCollisionHandlers[] = {
+    { ACTOR_PLAYER, ObjBoyo_PushPlayer },
+    { ACTOR_EN_KAIZOKU, ObjBoyo_PushPirate },
+    { ACTOR_EN_BOM, ObjBoyo_ExplodeBomb },
+};
 
-#pragma GLOBAL_ASM("asm/non_matchings/overlays/ovl_Obj_Boyo/func_809A5E24.s")
+void ObjBoyo_Init(Actor* thisx, PlayState* play) {
+    ObjBoyo* this = THIS;
 
-#pragma GLOBAL_ASM("asm/non_matchings/overlays/ovl_Obj_Boyo/ObjBoyo_Update.s")
+    Actor_ProcessInitChain(&this->actor, sInitChain);
+    Collider_InitCylinder(play, &this->collider);
+    Collider_SetCylinder(play, &this->collider, &this->actor, &sCylinderInit);
+    Collider_UpdateCylinder(&this->actor, &this->collider);
+    this->actor.colChkInfo.mass = MASS_IMMOVABLE;
+    this->animatedMaterial = Lib_SegmentedToVirtual(&object_boyo_Matanimheader_000E88);
+}
 
-#pragma GLOBAL_ASM("asm/non_matchings/overlays/ovl_Obj_Boyo/ObjBoyo_Draw.s")
+void ObjBoyo_Destroy(Actor* thisx, PlayState* play2) {
+    PlayState* play = play2;
+    ObjBoyo* this = THIS;
+
+    Collider_DestroyCylinder(play, &this->collider);
+}
+
+void ObjBoyo_PushPlayer(ObjBoyo* this, Actor* actor) {
+    Player* player = (Player*)actor;
+
+    player->pushedSpeed = 30.0f;
+    player->pushedYaw = this->actor.yawTowardsPlayer;
+}
+
+void ObjBoyo_PushPirate(ObjBoyo* this, Actor* actor) {
+    EnKaizoku* kaizoku = (EnKaizoku*)actor;
+
+    kaizoku->unk_2F0 = 30.0f;
+    kaizoku->unk_2F4 = Actor_WorldYawTowardActor(&this->actor, &kaizoku->picto.actor);
+}
+
+void ObjBoyo_ExplodeBomb(ObjBoyo* this, Actor* actor) {
+    EnBom* bom = (EnBom*)actor;
+
+    bom->timer = 0;
+}
+
+/*
+ * Find the Actor we collided with.
+ */
+Actor* ObjBoyo_FindCollidedActor(ObjBoyo* this, PlayState* play, s32* index) {
+    Actor* collidedActor;
+    ObjBoyoUnkStruct* iter;
+    s32 i;
+
+    if (this->collider.base.ocFlags2 & OC2_HIT_PLAYER) {
+        *index = 0;
+        return &GET_PLAYER(play)->actor;
+    }
+    iter = sCollisionHandlers + 1;
+    if (this->collider.base.ocFlags1 & OC1_HIT) {
+        collidedActor = this->collider.base.oc;
+        for (i = 1; i < 3; i++) {
+            if (iter->id == collidedActor->id) {
+                *index = i;
+                return collidedActor;
+            }
+            iter++;
+        }
+    }
+    return NULL;
+}
+
+void ObjBoyo_Update(Actor* thisx, PlayState* play2) {
+    PlayState* play = play2;
+    ObjBoyo* this = THIS;
+    Actor* collidedActor;
+    s32 index;
+
+    collidedActor = ObjBoyo_FindCollidedActor(this, play, &index);
+
+    if (collidedActor != NULL) {
+        sCollisionHandlers[index].colHandler(this, collidedActor);
+        // TODO: find out what all of these are.
+
+        this->unk194 = 0x64;
+        this->unk196 = 3;
+        this->unk198 = 0.01f;
+        this->unk19C = 0.03f;
+        this->unk1A4 = 0x3F40;
+        this->unk1A6 = 0x7D0;
+        this->unk1A8 = 0;
+        this->unk1A0 = 0.03f;
+        this->unk1AA = 0x2DF7;
+        this->unk1AC = 0x258;
+    }
+
+    if (this->unk194 > 0) {
+        // compute new scaling
+        // this computation might help finding what those values are.
+
+        this->unk194 -= this->unk196;
+        this->unk1AA += this->unk1AC;
+        this->unk1A8 += this->unk1AA;
+
+        this->actor.scale.x = this->actor.scale.z =
+            (Math_CosS(this->unk1A8 + this->unk1A4) * (f32)this->unk194 * this->unk19C * this->unk198) + 0.1f;
+
+        this->actor.scale.y =
+            (Math_CosS(this->unk1A8 + this->unk1A6) * (f32)this->unk194 * this->unk1A0 * this->unk198) + 0.1f;
+    } else {
+        Actor_SetScale(&this->actor, 0.1f);
+        if (this->collider.base.acFlags & AC_HIT) {
+            // TODO: find out what all of these are.
+
+            this->unk194 = 0x1E;
+            this->unk196 = 2;
+            this->unk198 = 0.033333335f;
+            this->unk19C = 0.012f;
+            this->unk1A0 = 0.006f;
+            this->unk1A4 = 0x3F40;
+            this->unk1A6 = 0x7D0;
+            this->unk1A8 = 0;
+            this->unk1AA = 0x3A98;
+            this->unk1AC = 0x640;
+        }
+    }
+    this->collider.base.acFlags &= ~AC_HIT;
+    this->collider.base.ocFlags1 &= ~OC1_HIT;
+    this->collider.base.ocFlags2 &= ~OC2_HIT_PLAYER;
+    CollisionCheck_SetOC(play, &play->colChkCtx, &this->collider.base);
+    if (this->actor.xzDistToPlayer < 2000.0f) {
+        CollisionCheck_SetAC(play, &play->colChkCtx, &this->collider.base);
+    }
+}
+
+void ObjBoyo_Draw(Actor* thisx, PlayState* play) {
+    ObjBoyo* this = THIS;
+
+    AnimatedMat_Draw(play, this->animatedMaterial);
+    Gfx_DrawDListOpa(play, object_boyo_DL_000300);
+}
diff --git a/src/overlays/actors/ovl_Obj_Boyo/z_obj_boyo.h b/src/overlays/actors/ovl_Obj_Boyo/z_obj_boyo.h
index feb95dcd13..eb1184a406 100644
--- a/src/overlays/actors/ovl_Obj_Boyo/z_obj_boyo.h
+++ b/src/overlays/actors/ovl_Obj_Boyo/z_obj_boyo.h
@@ -3,11 +3,21 @@
 
 #include "global.h"
 
-struct ObjBoyo;
-
 typedef struct ObjBoyo {
     /* 0x000 */ Actor actor;
-    /* 0x144 */ char unk_144[0x6C];
+    /* 0x144 */ ColliderCylinder collider;
+    /* 0x190 */ AnimatedMaterial* animatedMaterial;
+    /* 0x194 */ s16 unk194;
+    /* 0x196 */ s16 unk196;
+    /* 0x198 */ f32 unk198;
+    /* 0x19C */ f32 unk19C;
+    /* 0x1A0 */ f32 unk1A0;
+    /* 0x1A4 */ s16 unk1A4;
+    /* 0x1A6 */ s16 unk1A6;
+    /* 0x1A8 */ s16 unk1A8;
+    /* 0x1AA */ s16 unk1AA;
+    /* 0x1AC */ s16 unk1AC;
+    /* 0x1AE */ s16 unk1AE;
 } ObjBoyo; // size = 0x1B0
 
 #endif // Z_OBJ_BOYO_H
diff --git a/tools/disasm/functions.txt b/tools/disasm/functions.txt
index 85b13487cf..9ad15cf7d9 100644
--- a/tools/disasm/functions.txt
+++ b/tools/disasm/functions.txt
@@ -8743,10 +8743,10 @@
     0x809A5B50:("ObjArmos_Draw",),
     0x809A5D10:("ObjBoyo_Init",),
     0x809A5D94:("ObjBoyo_Destroy",),
-    0x809A5DC0:("func_809A5DC0",),
-    0x809A5DE0:("func_809A5DE0",),
-    0x809A5E14:("func_809A5E14",),
-    0x809A5E24:("func_809A5E24",),
+    0x809A5DC0:("ObjBoyo_PushPlayer",),
+    0x809A5DE0:("ObjBoyo_PushPirate",),
+    0x809A5E14:("ObjBoyo_ExplodeBomb",),
+    0x809A5E24:("ObjBoyo_FindCollidedActor",),
     0x809A5E98:("ObjBoyo_Update",),
     0x809A610C:("ObjBoyo_Draw",),
     0x809A6280:("EnGrasshopper_Init",),
diff --git a/tools/disasm/variables.txt b/tools/disasm/variables.txt
index b427905c9f..7fd394acc4 100644
--- a/tools/disasm/variables.txt
+++ b/tools/disasm/variables.txt
@@ -9366,10 +9366,9 @@
     0x809A5BF0:("D_809A5BF0","f32","",0x4),
     0x809A5BF4:("D_809A5BF4","f32","",0x4),
     0x809A6150:("Obj_Boyo_InitVars","UNK_TYPE1","",0x1),
-    0x809A6170:("D_809A6170","UNK_TYPE1","",0x1),
-    0x809A619C:("D_809A619C","UNK_TYPE1","",0x1),
-    0x809A61B0:("D_809A61B0","UNK_TYPE1","",0x1),
-    0x809A61B4:("D_809A61B4","UNK_TYPE2","",0x2),
+    0x809A6170:("sCylinderInit","ColliderCylinderInit","",0x1),
+    0x809A619C:("sInitChain","InitChainEntry","[]",0x4),
+    0x809A61AC:("gCollisionHandling","ObjBoyoUnkStruct","[]",0x20),
     0x809A61D0:("D_809A61D0","f32","",0x4),
     0x809A61D4:("D_809A61D4","f32","",0x4),
     0x809A61D8:("D_809A61D8","f32","",0x4),