Demon Slayer: Breathing Style? No, It’s Ultraviolet Light!

【Single Heroine or No Heroine + Science-Based Demon Slaying + World War I】 (Fresh new novel, come on in!) What would happen if the soul of a modern person transmigrated into Demon Slayer? “Everyone knows demons die when exposed to sunlight, and sunlight consists of infrared, visible, and ultraviolet light,” Hasumi Shigure murmured. “So what actually harms demons?” “It's not infrared. Muzan was nearly blown to bits and still regenerated, so it definitely isn't visible light either.” A vampire story he'd read long ago suddenly flashed through his mind. “It's ultraviolet! Ultraviolet light can kill demons outright!” Hasumi Shigure could even picture himself wielding an ultraviolet emitter and becoming a “human sun”... Ubuyashiki: “I'd only heard of this Western technology. I never imagined it would be so effective against demons...” Shinobu Kocho: “You're a lot like me, Shigure. Maybe we can walk a different path together.” Kokushibo: “You call this the sun... Blasphemy... The sun belongs only to the children of the gods...” Hasumi Shigure: “I know you can't stop thinking about your little sun Yoriichi, but come on, Big Bro. It's the Taisho era, and World War I has already started. The sun belongs to everyone now!” Muzan: “Sun, sun, sun, sun, sun, sun, sun, sun, sun, sun, sun...” Hasumi Shigure: “Come get some sun!” Making up for regrets. I'll do my best to keep the characters in character. If they're not, blame my writing skills. I'm determined to give this story a happy ending!