https://catharcity.wordpress.com/2017/11/04/one-night-one-day-one-year-one-lifetime-chapter-1/ If you ask me the ML in the story is Tsundure, because that term is character development process that depicts a person who is initially cold (and sometimes even hostile) before gradually showing a warmer, friendlier side over time.
I could only think of Last Game manga, sorry it's not a novel but I love the ML's cute and funny act of tsundere so much
♦ BG Death is the Only Ending for the Villain Doomed to be a Canon Fodder I Raised a Sick and Weak Prince Marrying the Soft-Hearted Villain The Kids Have Changed The Lady I Served Became the Master You've Got the Wrong House, Villain BL Later, He Became a Royal Healer My Vegetative Partner Opened His Eyes in Anger After I Ran Away One Useless Rebirth ♦ Good luck I put these on the even though not all had a tsundere tag but I think otherwise. Its up to you.
My Husband is Suffering from a Terminal Illness I’m sorry, it’s a BL novel, but if we are focusing on a story with a tsundere male lead, then this novel is undoubtedly the first one that comes to my mind! This coming from someone who is not very found of tsundere characters... But My Husband(...) just gave me the ultimate Tsun Character as the ML and I actually really enjoyed! I think this has a lot to do with the MC, a transmigrated person from the apocalipse that’s now in the setting of an entertainment novel, he’s very straightforward and smart, a bit cunning, and super shameless! He deals with ML’s tusundere personality with his shamelessness and even the mighty CEO has to admiti defeat. Even though the title is about a terminal illness (that the ML does have), up til the last translated chapter (65-ish, I think) there was no angst or very dramatic vibes regarding this issue. Actually, it’s really heartwarming how ML is slowly opening up to MC and willing to get treatment in order to be with his wife.
I only know shounen-ai with tsundere male lead : Those Years I Opened A Zoo https://www.novelupdates.com/series/those-years-i-opened-a-zoo/ From the current translation, i don't see any bl yet. And MTL-ling is horrible i can't even know who's and who. The title says it all.