Mitsuru is the fourth playable ally in battle, available from June 13th. Prior to this point, she has been serving as the Navigator until Fuuka takes over the role, leaving Mitsuru free to fight on the front lines.
She has the 2nd highest Magic stat out of the group, only behind Yukari Takeba, although she learns Ice Boost and Ice Amp, giving her the highest potential damage in the game before equipment, and even so only marginally behind Yukari (with an extra equipment slot) if all are given optimal equipment. In the addition of being able to deal powerful Ice attacks, there's also a mild chance she can inflict the Freezestatus effect, nullifying enemy evasion and increasing vulnerability to Critical hits from physical attacks. Her already high SP value can be sustained with Spirit Drain, a move that leeches SP from opponents, albeit this only recovers 15 SP per turn.
Despite having the lowest Endurance stat of the available party, her HP is rather high and helps balance out her survivability, compared to Yukari and Akihiko whom are fragile against enemy attacks. While her Strength is the second lowest in the game, her access to one-handed swords (P3/FES) or rapiers (Portable) provide a greater benefit in their utility than damage, coupled with her moderate Luck stat granting her a solid chance at scoring a Critical hit should the right equipment present itself. In Portable, she has access to the Kokuseki Senjin, which can allow her to have both Ice Boost and Ice Amp while having no accessory.
Mitsuru has access to two status ailment skills, Marin Karin and Tentarafoo, capable of inflicting Charm and Panic respectively. These skills will see most of their use in regular encounters, however certain floor bosses are susceptible to them as well, and can be very potent if they land. Charming them with Marin Karin gives the afflicted enemies a chance of distracting them from attacking, while Panic from Tentarafoo blocks them from using enemy skills. She is also able to heal one ally per turn. However, her use of support can delay her if used too regularly. This is most apparent in her affliction skills, as their low success rate will often require multiple turns to properly succeed.
One of Mitsuru's greatest strengths is how consistent her gameplan is. With access to passive boosts, her Ice damage is nearly unmatched, and she can focus on dealing high damage every turn thanks to her high SP pool. Much of her kit is built around maintaining her SP gauge rather than burning through it: Spirit Drain is an emergency means to get more SP, Mind Charge also allows her to conserve a bit of SP between turns. Unlike physical damage dealers, her HP is never required to deal said damage, resulting in a character that's moderately low risk for high reward. Ice Break extends this strategy to every opponent in the game with no exception, another advantage she possesses over her physical-based teammates (Junpei, Aigis, Shinjiro) or high damage magic users without an elemental Break (Akihiko).
While Mitsuru is, for many stretches, unmatched in her damage output, her rigidity lacks the depth much of the cast has at the cost of slightly lower damage, as she's lacking in support. Before level 45 (at which she learns Ice Boost), Yukari follows a very similar playstyle, albeit she has a wider variety of healing skills. Akihiko, for instance, learns his Boost skill six levels earlier than Mitsuru, and during these six levels deals more damage while having access to his debuff skills. Junpei will be dealing similar damage to her for the entirety of the game before unless she learns Ice Amp via skill or accessory, and will outdamage her on Critical hits regardless. Aside from that, he has double the affinity coverage, a passive regen, higher sustainability, and a party-wide defense buff. Mitsuru is excellent in a vacuum, but needs to maintain her edge or otherwise fall behind.
Additionally, her status effect skills are mostly a wild card, as it is not clear when an optimal time to use them presents itself. Unlike Ken and Koromaru's Hama/Mudo skills (which additionally have higher reward), the game has no indication as to how effective Charm/Panic skills are. Without extensive enemy knowledge or a guide, the downside to Mitsuru's skills is that they're hampered by a lack of information. In versions of the game without Direct Command, it's best to assign her to Full Assault or Knock Down to make the most of her unmatched firepower and minimize the risk of her wasting turns on ailment skills.
Mitsuru is strong against Ice, and is weak against Fire.
Mitsuru undergoes her awakening relatively late, triggering it on 18th November. Her Persona transforms into Artemisia, giving her Ice immunity and opening up the last few skills that she learns.
In The Answer, Mitsuru has an additional 8 points in every stat. This shifts the playing field quite a bit in her favor, and she now outdamages even Yukari. The lack of weapon fusion impacts Mitsuru arguably the least from FES The Journey to The Answer as well, and if anything only widens the damage gap she possesses now that Yukari, Junpei, and Ken no longer have access to Boost weapons, while Akihiko no longer has access to the Ice damage contender Sabazios.
Aside from her whopping 93 Magic, she also now possesses average Strength and Endurance, above average Agility, and the second highest Luck stat. If a high Critical weapon presents itself, she has the best chance of scoring a Critical hit, other than Junpei, on a more accurate weapon.
