Shizu

Shizu (full name Shizue Izawa) is a key early character in the anime That Time I Got Reincarnated as a Slime. She's a skilled adventurer and former Japanese Otherworlder who was summoned to the fantasy world as a child during World War II-era events.

In the anime, she appears as a young woman (looking in her 20s) with long black hair, black eyes, and distinctive red burn scars on part of her face, often wearing a mask to hide them and a practical adventurer's outfit. Despite her youthful appearance, she's actually much older (in her 70s or so by the time she meets Rimuru), as her body has been sustained unnaturally.

She's kind, friendly, gentle, and deeply caring—especially toward her students (a group of summoned children she taught and protected like a teacher/guardian figure). She views her immense fire-based powers (tied to the high-ranking spirit Ifrit, which possesses her) more as a curse than a blessing, due to the destruction and loss it has caused her.

Shizu is an A-rank (or A+) adventurer known as the "Conqueror of Flames" or similar titles for her explosive fire magic and combat prowess. She plays a pivotal role in Rimuru's early story, forming a meaningful connection with him as a fellow Japanese person from another world, sharing stories and ultimately entrusting him with her final wishes regarding her students and unfinished business. Her arc is emotional and tragic, emphasizing themes of loss, protection, and legacy in the first season.