Persona 4 Golden

Yukiko's Shadow is one of the first major bosses of the game outside of Chie's and Yosuke's shadows and for a real first boss, she's rather tough and even tougher if you don't come prepared. The recommended Level for this fight is 15 or higher.

Before coming into the fight, which occurs on the 8th floor of Yukiko's castle, there are a few preparations needed in order to increase your survivability. First, you're going to want a fire resistance skill, and a Persona for MC that has a natural resistance to fire. For the fire resistance skill, you're going to want "Red Wall", which grants fire resistance to one party member. You can get this skill by leveling up the Slime Persona up to Level 4, which shouldn't take very long.

Now that you have the skill you need, you now need a Persona to help mitigate fire damage. A good Persona to use would be Orobas, which can be obtained by fusing Slime with an Apsaras, another early game Persona you can obtain from Shuffle Time in Yukiko's castle. Make sure to transfer the Red Wall skill to Orobas. Note you need to be at least Level 8 in order to fuse Orobas.

It also wouldn't hurt to have a Persona that has the Rakunda skill to lower Yukiko's shadows defense to pair with Chie's Tarukaja. Izanagi, your starting Persona, learns that skill at Level 3 so you can pass that off, as well as Rakukaja, to another Persona to use as long as it doesn't have a fire weakness. Also if possible, have a healing Persona to pair with Yosuke to help keep up with healing.

After you have the necessary skills and Personas, the fight itself is pretty much a slugfest as Yukiko's Shadow is a damage sponge. More often than not, she'll use her first turn casting White Wall, to negate any Bufu based attacks which covers her weakness up. In that same turn, get Red Wall on Chie and have Chie power up whoever your main attacker will be, whether it's her or MC. Yosuke will mostly be used for support with Sukukaja and healing, throwing in physical attacks whenever he can.

Ideally you're going to want to throw your buffs on early in the fight before starting your assault, so get your Agility, defense, and attack up as much as possible before starting your attacks, and recasting Red Wall each time the effect wears off on Chie. Yukiko's Shadows big attack is a fire based attack that hits all characters for decent damage, so don't be afraid to spend a turn using healing items or using MC and Yosuke to heal up. After doing enough damage, she'll summon a minion to help her, which will cast buffs and heal her every now and then. Use Dekaja with either Orobas or Yosuke (which is learned at Level 10 for him) to get rid of any buffs Yukiko's Shadow gets as we don't need her to be any stronger than she already is and focus on damaging the minion until it runs away. One thing to note here is that if you are able to get a Bufu in on Yukiko's shadow, DO NOT use an all-out attack. Follow up with another Bufu as it will do more damage to her than the all-out attack would. Feel free to correct me if this is not the case, but I found that to be more efficient.

Once it's a 3v1 fight again, it's just repeating the same pattern again until you dwindle her health down; buff/debuff, use Red Wall, heal, and use Bufu if possible to get extra damage in (again, DO NOT use all-out attacks, just use a second Bufu instead), heal and repeat until you knock off all her health.

The achievement will pop a few days later in-game.