Prince Ryoma will wait patiently for his refine, but only for 25 months. After that, he will begin his dominance. (Enemy Phase Heal Tank)

Weapon: Raijinto (+Eff)

Assist: Reposition / flexible

Special: Noontime / Glimmer / Sol

IVs: +Spd / -Def

Passive A: Atk/Res Unity / Darting Breath / Kestrel Stance 3 / Atk/Spd Solo / flexible

Passive B: Spurn / Repel / Close Call / Wrath / Null C-Disrupt

Passive C: Pulse Smoke / Joint Drive Atk / Atk Smoke / Spd Smoke / flexible

Sacred Seal: Atk/Spd Solo / Mystic Boost / Spd/Res Solo / flexible

• Raijinto’s refine allows Ryoma to access the coveted combination of Null Follow-Up (in the weapon effect) and speed-based damage reduction from a skill such as Spurn, Repel, or Close Call. This increases his bulk significantly while rendering him immune to guaranteed enemy follow-ups and disabling effects that prevent his follow-ups, allowing him to function effectively as a tank. 
• The ideal B slot is one of Spurn, Repel, or Close Call, as Ryoma’s bulk is rather poor without the added damage reduction they provide. Spurn is arguably the best option, since the extra 5 damage on Special activation is potentially every combat on this build, and the movement effects from Repel and Close Call are generally not very useful and can even be counterproductive, depending on the mode Ryoma is used in. However, all three skills function similarly. Wrath can be used as a more budget option, but losing the damage reduction hurts his bulk massively. Null C-Disrupt could be used to allow him to counterattack units using skills such as Dazzling Staff or Firesweep effects, but Ryoma generally appreciates the damage reduction more, especially if using Mystic Boost seal. 
• Noontime is chosen to be used with some form of Special cooldown charge gain from an effect such as Darting Breath or another breath, or a support unit such as Brave Lucina, so that Ryoma can get attacked and immediately activate Noontime on the counterattack. Glimmer or Moonbow could be used instead of Noontime to boost Ryoma’s damage. If no Special cooldown charge gain effects are available, Sol can be used instead for a larger amount of healing. 
• The ideal choice of boon is +Spd, as Ryoma depends heavily on his Spd for damage reduction and follow-ups. +Atk is a decent option as well. Ryoma does not particularly want any bane, as he uses all his stats, but -Def is preferred to -Res or -HP since his base Def is higher than his Res, and damage reduction skills diminish the value of Def and Res compared to HP. 
• The choice of A slot is flexible. A Breath skill like Darting Breath may be used to accelerate Ryoma’s special activation, as described above. If this is unneeded or unavailable, Ryoma prefers options that boost his stats significantly while providing other useful effects, such as Atk/Res Unity, Kestrel Stance, or Atk/Spd Solo. 
• The choice of C slot is also flexible. Options like Joint Drive Atk and Pulse Smoke may be valuable to boost Ryoma’s damage or prevent enemy special activation, respectively. More budget options like Atk Smoke or Spd Smoke also provide a useful reduction in enemy stats after combat. 
• There are several good choices of seal as well. Mystic Boost heals 6 HP after combat while also disabling the Wrathful effect of staves, effectively causing them to do half damage against Ryoma. Atk/Spd Solo and Spd/Res Solo also provide large useful stat boosts under a fairly easy condition. Quick Riposte can be used to guarantee follow-ups against enemies that Ryoma does not have enough speed to double, so long as he is above 70% HP.