All the characters are in highschool, which means that they should be around the age of 18.
Nikolai is known to be the son of a family who emigrated from Russia to Japan. This means that Nikolai’s height should fall under the same average Russian male height which is around 5 feet and 10 inches. This average was derived from a World Population Review article which was published in 2022.
Nikolai is used as the main frame of reference for estimating the heights of all 4 heroines in the visual novel.
Catherine appears to be the tallest among the girls, being almost as tall as Nikolai. This was observed in this Kickstarter article which contains a photo of Catherine and Nikolai standing together. With this information, we estimate her to have a height of 5 feet and 8 inches.
Himitsu’s height was estimated by observing her in a photo from Pro Game Guides article. It appears that Himitsu’s maximum height would reach the lower nose of Nikolai, which means that she should be around 5’5 tall.
Ellie and Kagome’s height were both visualized from this Love, Money, Rock n Roll (LMR) official page.
As seen on Ellie’s character profile, there is a photo of her having a little accident where she appears to have accidentally bumped into Nikolai while holding some food. Using this photo as reference, we conclude that Ellie’s maximum height would reach Nikolai’s upper neck. When creating this estimate, we considered that fact that Nikolai was slouching a little bit which may have made it look like Ellie is around nose height level to Nikolai. Overall we give Ellie a maximum height only reaching the top neck/chin level of Nikolai, which means that she is about 5 feet and 3 inches tall.
As for Kagome, it can be seen on her character profile that she is much smaller compared to Nikolai. Her maximum height appears to be shoulder level to Nikolai, therefore we give her an estimated height of 5 feet (150cm).
Hikaku Sitatter’s height comparison chart was used to visualize the heights of all four heroines.