The Genius of Sappheiros: Character Quests Byakuren

Quest information

 * Quest name: 泥舟遊覧
 * Quest portrait: Byakuren
 * Location: Stage 14
 * Team restrictions: None
 * Difficulty: 3

Treasure Chests
Southeast - B
 * Fresh Blood 生き血

West - C
 * Sewing Needle 裁縫針

Northwest - D
 * Eyeball 眼球
 * Steel 鋼鉄

Boss battle: Byakuren Hijiri and Minamitsu Murasa
Byakuren's HP: 17000 Murasa's HP: 28000

A frustrating pair despite their low HPs. Byakuren will set up Complete Protection on herself in turn 1 (and whenever it wears off), which gives her 100% divine barrier (aka you cannot do any damage to her without exorcism), and starts flinging you with debuffs. Give her some turns and she will start attacking you with light and dark elemental spells that are strong.

Murasa, on the other hand, attacks you with not only normal, weak skills, but also anchors. Each anchor generally does something at the end of each turn, such as inflicting a random status or healing both Byakuren and Murasa for 1/4 of their MaxHP (4250 and 7000, assuming you didn't put Sanae's MaxHP buff on them for some unknown reason). When her HP is down by 50%, she will be able to use Final Anchor, which will put 最終錨 on the field, which will do 999 damage to your entire party at the end of second turn. Since it's a field spell, you can overwrite it with another before it activates, and Mokou's reraise will save you, but that's about it.

You can ignore Complete Protection if your party members all have weapons with high exorcism rate. Otherwise, you will want to bring someone capable of dispelling (anyone who can equip a staff can put 13 points in the tree to get a dispelling magic) and have her dispel Byakuren's barrier every turn so you can actually do damage to her, and someone with a field spell (Aya is the easiest option) to nullify Murasa's Final Anchor if you're unlucky enough to see it. Kill Byakuren first, while hoping that Murasa doesn't set up her healing anchor too much. If you can get Byakuren down, you've got most of the battle won already, since Murasa's no threat by herself as long as you can nullify final anchor.

After the battle, Byakuren will rejoin your party.

Alternative Strategy: I was completely unprepared for Complete Protection when I came to this boss fight, with no means of applying Exorcism or dispel. I killed Murasa while I waited for the 9 turns of Complete Protection to expire. Then I killed Byakuren in one turn before she re-cast it, with Aya to make sure Byakuren went last and Nitori's all-type chaser doing all the work while everyone else opened up their multi-target attacks. Set up Peerless Wind God so Aya can contribute to the chaser's damage output instead of having to cast Illusionary Dominance.