ALIN-EN090 – Mitsurugi no Mikoto, Aramasa
Level 4 DARK Reptile Effect Monster
ATK 1200
DEF 900
If this card is Normal or Special Summoned, or if this card is Tributed: You can add 1 “Mitsurugi” monster from your Deck to your hand, except “Mitsurugi no Mikoto, Aramasa”. If another Reptile monster(s) you control would be destroyed by battle or card effect, you can Tribute this card instead. You can only use each effect of “Mitsurugi no Mikoto, Aramasa” once per turn.

Note: The Worochi-no-Aramasa is the name for a Totsuka-no-Tsurugi, a sword the length of the breadth of ten hands, wielded by Susanoo to slay the monster Orochi. It is enshrined at Isonokami Shrine.

ALIN-EN091 – Mitsurugi no Miko, Wousu
Level 8 DARK Reptile Effect Monster
ATK 2000
DEF 2000
You can Special Summon this card (from your hand) by Tributing 1 other Reptile monster from your hand and 1 monster your opponent controls, but you cannot Special Summon nor activate monster effects for the rest of this turn, except Reptile monsters. You can only Special Summon “Mitsurugi no Miko, Wousu” once per turn this way. If this card is Tributed: You can discard 1 card, and if you do, add this card to your hand. You can only use this effect of “Mitsurugi no Miko, Wousu” once per turn.

Note: This card refers to Yamato Takeru no Mikoto, originally Ousu no Mikoto, a Japanese folk hero and semi-legendary prince. He’s listed as a Miko because he dressed as a maid attendant once to slay a powerful chieftain.

ALIN-EN092 – Ame no Habakiri no Mitsurugi
Level 8 DARK Reptile Ritual Effect Monster
ATK 2400
DEF 1800
You can Ritual Summon this card with “Mitsurugi Ritual”. Monsters your opponent controls lose 800 ATK. You can reveal this card in your hand; Special Summon 1 “Mitsurugi” monster from your Deck, then Tribute 1 monster you control. You can only use this effect of “Ame no Habakiri no Mitsurugi” once per Duel. If this card is Tributed: You can add 1 “Mitsurugi” card from your Deck to your hand, except “Ame no Habakiri no Mitsurugi”, then you can Special Summon this card. You can only use this effect of “Ame no Habakiri no Mitsurugi” once per turn.

Note: The Ame-no-Habakiri is another name for the Worochi-no-Aramasa.

ALIN-EN093 – Mitsurugi Mirror
Ritual Spell Card
This card can be used to Ritual Summon any Reptile Ritual Monster from your hand or GY. You must also Tribute Reptile monsters from your hand or field whose total Levels equal or exceed the Level of the Ritual Monster. If “Ame no Murakumo no Mitsurugi”, “Futsu no Mitama no Mitsurugi”, or “Ame no Habakiri no Mitsurugi” you control is Tributed, while this card is in your GY: You can shuffle this card into the Deck. You can only use each effect of “Mitsurugi Mirror” once per turn.

Note: 神鏡 is the term for a sacred mirror in Shinto, used as a sacred object of the Kami, or ae placed in front of the Kami in the hall of worship. This is because mirrors are typically seen as sources of truth, because they reflect what is there.

This card is likely a reference to the Yata-no-Kagami, one of the three sacred treasures of the Imperial Regalia.

ALIN-EN094 – Mitsurugi Magatama
Quick-Play Spell Card
During the Main Phase: Activate 1 of these effects;
●Tribute 1 Reptile monster, then target 1 face-up card your opponent controls; destroy it.
●Ritual Summon 1 “Mitsurugi” Ritual Monster from your hand, by Tributing monsters you control whose total Levels equal or exceed its Level.
You can only activate 1 “Mitsurugi Magatama” per turn.

Note: Magatama are curved beads that began appeearing in Japan from the end of the Jomon era through the Kofun era (basically 1000 BCE to 600 CE). They originally served as jewlery but by the end were ceremonial and religious objects made of jade.

This card is likely based on the Yasakani-no-Magatama, one of the three sacred treasures of the Japanese Imperial Regalia.

ALIN-EN095 – Mitsurugi Sacred Boundary
Continuous Spell Card
Your opponent cannot target “Mitsurugi” Ritual Monsters you control with effects of monsters that were Special Summoned from the Extra Deck. You can target 4 “Mitsurugi” cards in your GY, except “Mitsurugi Sacred Boundary”; shuffle them into the Deck, then if your opponent controls a monster, make them Tribute 1 monster they control (their choice). You can only use this effect of “Mitsurugi Sacred Boundary” once per turn.

Note: Iwasaka is a mythical Iwakura, a rock-as-Yorishiro that enshrines a Kami. Or a Stone altar or mound erected as a Yorishiro to worship a Kami.

ALIN-EN096 – Mitsurugi Tempest
Normal Trap Card
If you have a “Mitsurugi” Ritual Spell in your GY: Tribute 3 monsters whose original names are “Ame no Murakumo no Mitsurugi”, “Futsu no Mitama no Mitsurugi”, and “Ame no Habakiri no Mitsurugi”; make your opponent banish exactly 8 cards from their hand, Extra Deck, field, and/or GY. You can only activate 1 “Mitsurugi Tempest” per turn.

Note: Yakumotatsu seems to reference part of the story of Susanoo, basically saying a sword swing that can cut through 8 (i.e. many) clouds 

Source: Alliance Insight Set Introduction Stream