Arena Mode
Arena Mode (アリーナモード Arīna Mōdo) is a feature that appears in Kingdom Hearts Birth by Sleep. It allows players to fight a series of set matches against enemies. It can be played either as a single-player mode or as a multiplayer mode over a wireless connection with up to three participants. As with other events occurring in the Mirage Arena, players appear as Terra, Ventus, or Aqua, wearing their Keyblade Armor, rather than their usual gameplay attire.
Other players' HP bars are displayed above the protagonist's own sprite, similar to party members, and their names are shown above their characters.
In the Kingdom Hearts HD 2.5 ReMIX version, Arena Mode is only available in single-player mode, due to the removal of a multiplayer function. The difficulty of the matches has been toned down to accomodate solo fights.
Gameplay
In the Hub area, players choose a battle and proceed by standing in the center spot. Each battle has a Risk (ランク Ranku, lit. "Rank") rating between 1 and 5 stars, showing the difficulty.
When playing with friends, players can team up when using certain Friendship commands to deal more damage. If a player's HP drops to 0, other players can revive that player by repeateadly pressing 
to fill a gauge and trigger Healing Light (ヒールライト Hīru Raito, lit. "Heal Light").
At the end of a match, players are ranked in three categories: Damage, Friendship, and Style, with 1st place getting 2 points, and 2nd place getting 1 point. The player with the most points is crowned the MVP, and has the number of Medals earned multiplied by 1.5. The Damage category is determined by which player dealt the most damage to enemies. The Friendship category is determined by which player has used the most Group Cure or Group Esuna commands, and has pressed the button the most during Healing Light. The Style category is determined by which player activated the most Command Styles and Shotlocks. In Kingdom Hearts HD 2.5 ReMIX, the ranking has been replaced with a specific Bonus Challenge for each match, which multiplies the earned Medals when achieved.
Battles
| Match | Risk | Rounds | Medals Earned | Unlocked | Bonus Challenge[KH II HD] |
|---|---|---|---|---|---|
| Day of Reckoning (審判の時 Shinpan no Toki, lit. "Time of Judgment") |
★☆☆☆☆ | 4 | 50 | Initial | Tough as Nails: Heal 5 times or less. |
| Wheels of Misfortune (呪いの輪廻 Noroi no Rin'ne, lit. "Cursed Wheels") |
★☆☆☆☆ | 4 | 60 | Terra/Ventus: Clear the game with Aqua Aqua: Initial |
Down to the Wire: Complete this battle within 6:00. |
| Risky Riches (財宝のありか Zaihō no Arika, lit. "Treasure's Hiding Place") |
★☆☆☆☆ | 3 | 70 | Arena Level 8 Risky Ticket |
Rags to Riches: Obtain at least 1400 munny. |
| Weaver Fever (駆ける紡ぎ手 Kakeru Tsumugi-te, lit. "Gallopping Spinning Hand") |
★★☆☆☆ | 4 | 80 | Terra: Initial Ventus/Aqua: Clear the game with Terra |
Practices Make Perfect: Perform a combined total of at least 8 Style Changes and Shotlocks. |
| Sinister Sentinel (牢獄の番人 Rōgoku no Ban'nin, lit. "Prison Guard") |
★★☆☆☆ | 5 | 100 | Arena Level 3 Sentinel Ticket |
Lightning Reflexes: Successfully block enemy attack at least 20 times. |
| Dead Ringer (幻惑せし者 Genwakuseshisha, lit. "Dazzler") |
★★☆☆☆ | 5 | 120 | Arena Level 5 Ringer Ticket |
Tough as Nails: Heal 3 times or less. |
| Combined Threat (集いたる暴君 Tsudoitaru Bōkun, lit. "Gathered Tyrant") |
★★★☆☆ | 6 | 140 | Clear Radiant Garden Clear the game with anyone Threat Ticket |
Down to the Wire: Complete this battle within 5:30. |
| Treasure Tussle (欲を見つめる目 Yoku o Mitsumere Me, lit. "Eyes Gazing on Desire") |
★★★☆☆ | 3 | 160 | Arena Level 15 Treasure Ticket |
Rags to Riches: Obtain at least 1750 munny. |
| Harsh Punishment (振り下ろされた罰 Furiorosareta Batsu, lit. "Punishment Swung Down") |
★★★☆☆ | 6 | 200 | Arena Level 10 | Tough as Nails: Heal 3 times or less. |
| A Time to Chill (凍える息吹 Kogoeru Ibuki, lit. "Chilled Breath") |
★★★★☆ | 8 | 250 | Terra/Ventus: Clear the game with Aqua Aqua: Clear Olympus Coliseum Aqua: Chill Ticket |
Lightning Reflexes: Successfully block enemy attack at least 50 times. |
| Copycat Crisis (幻影の魔術師 Gen'ei no Majutsushi, lit. "Conjurer of Illusions") |
★★★★☆ | 8 | 300 | Arena Leve 17 | Practices Make Perfect: Perform a combined total of at least 15 Style Changes and Shotlocks. |
| Keepers of the Arena (闘技場の支配者 Tōgijō no Shihaisha, lit. "Rulers of the Arena") |
★★★★★[KH BbS] ★★★★☆[KH BbS FM] |
9 | 400 | Arena Level 20 | Tough as Nails: Heal 15 times or less. |
| Monster of the Sea (大海原の怪物 Ōunabara no Kaibutsu, lit. "Monster of the Ocean")[KH BbS FM] |
★★★★☆ | 8 | 450 | Arena Level 8 | Down to the Wire: Complete this battle within 7:30. |
| Villains' Vendetta (覇者の復讐 Hasha no Fukushū, lit. "Titleholder's Revenge") |
★★★★★ | 8 | 500 | Arena Level 30[KH BbS] Arena Level 25[KH BbS FM] |
Practices Make Perfect: Perform a combined total of at least 25 Style Changes and Shotlocks. |
| Light's Lessons (光の訓導 Hikari no Kundō, lit. "Guidance of Light")[KH BbS FM] |
★★★★★ | 1 | 800 | Arena Level 28 | Lightning Reflexes: Successfully block enemy attack at least 100 times. |
| Peering into Darkness (闇への遠謀 Yami e no Enbō, lit. "Foresight unto Darkness") |
★★★★★ | 1 | 1000 | Arena Level 30 | Down to the Wire: Complete this battle within 25:00. |
Gallery
A player reviving an ally with Healing Light.
Three players teaming up to use Trinity Limit.
