Hello everyone and welcome to my 189th analysis, this time featuring Oikawa.
Oikawa is a tank/attacker hybrid that is effective at both of these. If a massive 41k Life is not an indicator, then maybe 2 Taunt moves and access to healing will persuade you. As for the attacker part, he has moves that give him Double Damage and Base 40 and 45 AOEs. His trait, Hardened, also makes him resilient against all kinds of status which is key for a tank. However, being placed in Underworld is very unlucky, as the two titan tanks, Ouros and Igursus, are both there, and especially Igursus can make mincemeat out of Oikawa. Evil Legions is not a very friendly environment either, as the massive amounts of brokenness disable any tank from working properly there.

Runes: 1 Strength 1 Speed 1 Life/2 Life 1 Speed

Sekitori heals him by 40%, removes all debuffs from him, and gives him both Taunt and Double Damage, though Jonokuchi is an extremely powerful self move that doesn't give Taunt and heals by 10% less, but has 0 CD. Hazuoshi is used over Tsuppari for the chance at Stun. Nekodamashi makes Oikawa immune to almost all forms of denial and gives him Taunt, but Jonokuchi can be used here as well. Lastly, Kimarite vs. Nodowa is a mater of power vs. CD. A rainbow spread compliments his attacker side, but 2 Life 1 Speed is also acceptable since Double Damage is enough to make him hit hard, though don't expect one-shots at higher ranks this way.

Teammates: If you can give Oikawa Double Life, he will be a chore to deal with as Double Life+Taunt is pretty hard to deal with. Even a Damage Boost, when combined with Double Damage, can allow Oikawa to one-shot enemies with 1 Strength rune.

Countering Oikawa: Igursus is very effective against him since he can Burn and apply Quicksand. Ouros vs. Oikawa is an obvious victory for the former if it comes down to it. Despite his tankiness, Zyla the Faithful can break through him, and Llum can remove all of his buffs. General Darmith doesn't care much about Double Damage thanks to Dragon Berserker, and Final Flare boosted by Double Damage will deal insane damage, not to mention it goes through Taunt thanks to being an AOE.