The new update has a bunch of new items, in this page I will detail what was added and where you can find it in the code.

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Kuge culture, found under Defs/CultureDefs/HSCultureDef.XML
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Black powder bomb and kunai, found under Defs/ThingDefs_Misc/HSBasicRangedWeapons.XML
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Bokken found under
Defs/ThingDefs_Misc/HSBasicWeapons.XML
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Clanforged Nagamaki found under
Defs/ThingDefs_Misc/HSClanforgedWeapons.XML
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tenbinbō , found under
Defs/ThingDefs_Misc/HSUtility.XML
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Veterans Kabuto, prestige Kabuto, Workers headband, Shinobi Halfmask, Hannya mask, found under
Defs/ThingDefs_Misc/Apparel_Headgear_HS_Samurai_Armor.XML
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Heavy Do, found under
Defs/ThingDefs_Misc/Apparel_Various_HS_Samurai_Armor.XML
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Legendary Katana, found under
Defs/ThingDefs_Misc/HSSpecialWeapons.XML
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The legendary Katana has a rule pack for naming it, found under
Defs/RulePackDefs/HSRulePacks_Namers_Weapons.XML
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Andon, Throne, Tatami, Fancy futon, fancy futon double, found under
Defs/ThingDefs_Buildings/HSBuildings_Miscbuildings.XML
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The koto was ported over, it is found in
Defs/ThingDefs_Buildings/HSBuildings_MusicalInstruments
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Small Irori found in
Defs/ThingDefs_Buildings/HSBuildings_Production
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The Banzai ability, which has files found in
Defs/AbilityDefs/HSAbilityDefs.XML and Defs/HEdiffDefs/HSHediff_Casts.XML and
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Permits and royal titles, both found in the folder
Defs/RoyalTitles
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A new faction, found under
Defs/Faction_Defs/HSFactions_Royalty.XML
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New pawnkinds, found under
Defs/PawnKindDefs/HSPawnKinds_Player.XML
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OKAY, I think that's about it. Ill add a comment to amend it if I forgot anything.