I believe the title of this anime should already alert you to some of the things that are found in it. The whole story is about a guy who finds an unsigned love letter addressed to him with a girl's undergarments. He tries to figure out who gave them.
Perverted
As the name suggests, the women found in this show are "perverts." This show would be considered an ecchi anime. Women's undergarments are used as "gifts" to the main character, Keiki.¹ Additionally, women are seen in their undergarments and cleavage/thighs are shown often.¹
"In like manner also, that women adorn themselves in modest apparel, with shamefacedness and sobriety; not with broided hair, or gold, or pearls, or costly array;" (1 Timothy 2:9)
People touch each other inappropriately and there are a lot of sexual innuendo¹ (including BDSM).
"[3] For this is the will of God, even your sanctification, that ye should abstain from fornication: [4] That every one of you should know how to possess his vessel in sanctification and honour; [5] Not in the lust of concupiscence, even as the Gentiles which know not God:" (1 Thessalonians 4:3-5)
Here, we are told that God's will is for us to become sanctified. He says that we should "abstain from fornication" and to possess our bodies in a sanctified and honorable way instead of that of lust. Touching another person like that, while unmarried, is wrong.
Pedophilia
Within the context of things perverted in this show, there is a "lolicon pornbook".¹ That is disgusting and utterly wicked. If you're unaware of what lolicon is, it is a genre of Japanese media that sexualizes prepubescent children. This is deranged and wicked.
Conclusion
There is a lot of sexual perversion in this anime. As such, there is no real reason a Christian should watch something like this.
Sources:
1. "Hensuki: Are you willing to fall in love with a pervert, as long as she's a cutie?: Parents guide." IMDb, imdb.com/title/tt10470356/parentalguide. Accessed 25 Jan. 2025.