“Koshashin” means “old photo”. “Bakumatsu” is literally “end of feudal era”, the end of Edo shogunate era (circa 1860), when the whole country was facing to its turning point to open for outside of islands, led to Meiji Revolution. So the service name implies “Generator for photos like over 150 years old”.
You may easily upload and convert your photo. The image will not only become monochrome but also applied fading and staining effects to make it legitimate-looking old photo.