Can you raise the stars of characters in Honkai Star Rail?

sportskeeda.com:

Honkai Star Rail features a robust gacha system for its characters and weapon equivalent - the Light Cones, much akin to its elder sibling Genshin Impact. Characters and Light Cones obtainable via the gacha range from 3-star to 5-star rarities and have unique properties. No two items are the same, even though it is wholly possible to pull duplicates of the same item.

As such, it is reasonable to think that these units may possess a hidden mechanism to increase their rarity, which is sadly not true in Honkai Star Rail.

Players looking to raise the rarities of their characters from 4-star to 5-star will be sorely disappointed, knowing that the base star level of a character is fixed from the start. All characters in Honkai Star Rail come with a set base star level that cannot be altered by any means, either by grinding materials or spending via in-app purchases.

As such, natural 5-stars are a fair bit more valuable owing to their rarity in the game. However, this does not mean that all 4-star characters are useless - in fact, it is quite the contrary, with 4-star units such as Serval and Tingyun capable of carrying teams in endgame content with relative ease.

Unless HoYoverse decides to progressively increase the rarity of a unit or release a unit whose rarity can be “ascended” progressively, this feature is unlikely to ever come to fruition.

While there is no way to ascend a 4-star character into a 5-star, eager players can invest in the following stats and character progression milestones to close the gap between the rarities. Although, it should be kept in mind that each unit is specifically hand crafted and fills their own niche and is not directly comparable to another unit, at the time of writing this article:

Honkai Star